Depends what you're doing.

My favourite knot is the bowline. Non-slip loop, very strong, easy to tie, easy to undo. Can be used for tying two ropes together, ropes to things.

Other useful ones (especially for sailing)

* Clove hitch * Reef knot * Rolling hitch * Sheet bend

The marlinspike hitch is the best bang-for-your-buck. The author of this video shows it in quite a few of his other videos. Depending on what you do with the tag end, you can quickly collapse it into a bowline for a fixed loop (and subsequently apply any bowline finishing you might like), or you can end up with an Ashley stopper (which provides triple the diameter of the rope, so is an excellent stopper). Using it actually as a marlinspike hitch gives you a really nice handle to pull in tension on a trucker’s hitch. The knot also does not jam, so you can easily pull it out just by completely tightening it. This same property makes it an excellent choice for the loop in a trucker’s hitch… provided you get the directionality right so the force of pulling in tension counteracts its desire to collapse. When you’re done, the loop can just collapse out when you untie it—no dealing with a jammed alpine butterfly.

Bowline, truckee’s hitch (the better alternative to a truckers hitch), prussick come to mind

Love this "auto" truckers hitch: https://www.youtube.com/watch?v=1J8MuOWO0Qs

Edit: Same knot, with an explanation before showing what I knew as the classic trucker hitch https://www.youtube.com/watch?v=TKM5gaYJWN0

The Farrimond Hitch is my favorite knot. Useful to tie a line to another line and have it adjustable, but strong under load and a single pull to undo it. Easy to remember, it's like a prusik knot.

https://www.animatedknots.com/farrimond-friction-hitch-knot

(overhand and double 8 are probably used more often by me, but not that versatile)

There are (I'd contend) four basic types of knot: Bends, hitches, bindings, and loops. Bends tie two cords together, hitches tie cords to objects, bindings wrap & grip objects together, and loops are loops.

You only really need one bend. I suggest the zeppelin bend, but they're all pretty similar. Hitches can benefit from a bit more variety, but a round-turn with two half-hitches will serve you well in most situations, along with its more secure variant, the anchor hitch. There's a trade-off between how secure a knot is and how easy it is to untie, which is why the less-secure variant is useful.

The best loop is the angler's loop, which will even hold in bungee cord. The alpine butterfly is also good to know because you can tie it "in the bight" (without access to either end of the rope), which is very handy.

Bindings are (I think) the most commonly-used family of knots for most people. Lashing a load into a truck so it won't move, tying a bag shut, and even tying shoes are all situations for bindings. For large loads, I'd suggest a trucker's hitch, which is good for (e.g.) tightly strapping a load into a truck bed, hence the name. For smaller situations, like cinching a bag shut, try the jam hitch—an underappreciated favourite of mine. It works like a zip tie, tightening around an object and not loosening. (Make sure the knot itself is tied tightly before you zip it. After you zip it, you can tie the ends together for extra security.)

Zeppelin bend: https://www.animatedknots.com/zeppelin-bend-knot

Anchor hitch: https://www.animatedknots.com/anchor-hitch-knot; round turn & two half-hitches: https://www.animatedknots.com/round-turn-two-half-hitches-kn...

Angler's loop (sometimes called "perfection loop"): https://www.animatedknots.com/perfection-loop-knot; alpine butterfly: https://www.animatedknots.com/alpine-butterfly-loop-knot.

Trucker's hitch (feat. alpine butterfly): https://www.youtube.com/shorts/o3BcaoPXK5Q; jam hitch (aka "rolling hitch zip tie" or "reverse midshipman's hitch"): https://www.reddit.com/r/knots/comments/12vsuk1/how_to_tie_a.... (Though these have "hitch" in the name, I'd argue they're better described as bindings, because they preserve tension.)

If nothing else, learn the round turn & two half hitches, the alpine butterfly, and the trucker's hitch. Some combination of these will serve you well in most situations.

One final tip, while I'm talking about knots. You may be tying your shoelaces wrong: https://www.fieggen.com/shoelace/grannyknot.htm.

There is a reason scouts require you to tie so many knots. Not that any scout remembers their knots longer than needed pass that requirement, but it is still important and once in a while they do need them.

IMO it's important to start with what possible uses of knots there are, and then learn a knot for each use. I'll exclude decorative knots, because those are subjective & very diverse.

Stopper knots prevent rope from passing through a hole & keep the end from unraveling. The Overhand knot is the simplest. The Double Overhand is a very simple addition to an overhand. The Figure-8 is slightly bigger, and useful to know.

Single loop knots create a single fixed loop in a line. The Butterfly (aka Alpine Butterfly) can be tied mid-line (without access to the end) or with the end of a rope, and is two overhand knots interlocked in a particular manner.

A noose is any loop that tightens when a load is applied. I like the Scaffold Knot, it's a double overhand around the standing part of the rope. Its biggest disadvantage is it can be difficult to undo. Any fixed loop can also be made into a noose by tying it around the standing part, forming a "Running <name of fixed loop>".

Bends join the ends of two ropes. The Fisherman's knot (also has lots of other names) is two overhand knots, one with each rope, tied around the standing part of the other rope. It's strong, secure, but difficult to untie. The Double Fisherman's uses double overhands. The Butterfly Bend is a Butterfly tied as a bend, it's strong, secure, and much easier to untie. The Butterfly Bend is tied the same way the Butterfly Loop is when tying with the end.

Hitches tie a rope to a rigid object. They can attach a rope to something where you have access to an end of the object like a bollard, or where you don't like tying into a fixed ring. They can be for lengthwise pulls, or for right-angle pulls. Adjustable loops are hitches tied around the standing part of the rope. For right-angle pull, the scaffold knot works well (again). It can be tied without access to the end of an object, so it works for rings and bollards. For lengthwise pull, the rolling hitch is nice, and the Rolling Hitch Ziptie is a use of the rolling hitch which works as an adjustable loop and a binding knot.

Binding knots hold only when tied around an object. The Double-Slipped Reef Knot is a common shoelace knot. The Turquoise Turtle or "Ian's Secure Shoelace Knot" are different methods of tying a structurally identical resulting knot that's a bit more secure. Worth knowing at least one of these three, or you'll only wear slip-ons or Velcro closure shoes. Also the Rolling Hitch Ziptie is worth knowing.

There are also some systems of knots called "trucker's hitch"es, which are all ways to use loop knots as improvised pulleys with a final hitch to secure a load in place. IMO they're not independent knots. Handy to know at least one sort though in case you don't have ratchet straps or snatch blocks. The Versatackle is nice, self-locking, and tied with just Alpine Butterflies and any hitch.

So, a list of 5:

1: Overhand knot. 2: Butterfly loop (mid-line). 3: Butterfly loop (with the end). 3 (used differently): Running Butterfly. 3 (used differently): Butterfly bend. 4: Scaffold knot. 5: Rolling Hitch. 5 (used differently): Rolling Hitch Ziptie. 5 (used differently): two opposed Rolling Hitches for tying your shoelaces together works, with difficulty. 2+5: Versatackle trucker's hitch formed from two Butterfly loops and a Rolling Hitch.

All except the Rolling Hitch are based on the Overhand knot. If you're willing to add a sixth knot, pick something better to tie your shoes.

I've spent waaay to much time thinking about this over the past few years and have really gotten into knots.

Personally I'd say you need to classify the type of knots you want to learn and pick one knot from each. The classics in my opinion are

1. End loop

2. Mid loop

3. Hitch (opposite of an end loop)

4. adjustable loop

5. Bend (rope to rope)

My suggestions in order are

# End Loop

1a. Bowline (snap variant) - This is a knot that's super easy to tie, remember, and untie. There are a bunch of variants to expand it's usefulness (double, water, slip, yosemite, etc)

1b. Zeppelin Loop - this is my personal favorite, it's a little tricky to tie but I've never seen it slip and it unties easily after it's all done.

# Mid Loop

2a. Alpine Butterfly - learn the butterfly method and this is an easy to tie knot that can be easily sized. It also doesn't bind so it unties easily and can be loaded in any direction (on of the only midline knots this is true for)

2b. Bowline on a Bight - Super satisfying knot to tie, a little wonky to learn just because of the structure but easy to tie once you get it.

# Hitch

3a. Tensionless Hitch - (this is probably the most overlooked 'knot' just look at a diagram you can learn it and never forget it after seeing the diagram once. It's the strongest knot there is if you have the rope for it. (I wouldn't really count this at one of your 5 but it's good to keep in mind)

3b. Buntline Hitch - dead simple and you can usually untie it after a heavy load 3c. Siberian Hitch - This is effectively a slipped noose but I use it all the time, it's my personal go to.

3c. Poachers knot - If you have a carabiner or know you're never going to need to untie this knot it's hard to beat

# Adjustable Loop / Friction Hitch

4a. Adjustable Grip Hitch - Easy to learn and holds better than the Midshipman's

4b. Midshipman - it's a little more complicated but this was Ashley's favorite because it can be tied under tension

# Bend

(Bends and fixed loops usually have the same structure so you might not need this one)

5a. Zeppelin Bend - seriously just learn this one, sixty nine method is the easiest for me. Knot is easy to tie, doesn't slip, and is easy to untie.

5b. Sheet Bend - this knot... is fine but you already know it if you learned the bowline above as it's the same structure

Bonus Section

1. Trucker/Truckee - probably one of the most useful knots around, learn the method that uses a slip knot for the mid loop and it'll make even easier

2. Canadian Jam Knot - Useful for bundling things, it's a knot I find myself using a lot

3. Voodoo Hitch - You can use it in place of a ratchet strap if you have a couple of carabiners

4. Icicle Hitch - Ever wanted to tie a rope to a butter metal pole and keep it from slipping? This is the knot, it cinches and grips things with so much friction you can tie a rope to about anything vaguely cylindrical