1 = no privacy from relay

2 = risk of collusion between relays

3 = goldilocks default

4 = ... actually, you have more attack surface and you are more susceptible to fingerprinting because everybody else is using 3, so you're timings etc help identify you

So the default is 3 and nobody ought change it! Use 3 like everybody else.

The exception is .onion sites. TOR actually deliberately defaults to 6 hops when accessing .oninon sites - 3 to protect you and 3 to project the site.