Leading this by saying I've only used Ida free, I can't comment on Ida pro. I'm also a very lite user of both, I give name functions/vars, save bookmarks, and occasionally work out custom types, and that's about it, none of the real fancy stuff.

I was recently trying to analyse a 600mb exe (denuvo/similar). I wasted a week after ghidra crashed 30h+ in multiple times. A seperate project with a 300mb exe took about 5h, so there's some horrible scaling going on. So I tried out Ida for the first time, and it finished in less than an hour. Faced with having decomp vs not, I started learning how to use it.

So first difference, given the above, Ida is far far better at interrupting tasks/crash recovery. Every time ghidra crashed I was left with nothing, when Ida crashes you get a prompt to recover from autosave. Even if you don't crash, in general it feels like Ida will let you interrupt a task and still get partial results which you might even be able to pick back up from later, while ghidra just leaves you with nothing.

In terms of pure decomp quality, I don't really think either wins, decomp is always awkward, it's awkward in different ways for each. I prefer ghidra's, but that might just be because I've used it much longer. Ida does do better at suggesting function/variable names - if a variable is passed to a bunch of functions taking a GameManager*, it might automatically call it game_manager.

When defining types, I far prefer ida's approach of just letting me write C/C++. Ghidra's struct editor is awkward, and I've never worked out a good way of dealing with inheritance. For defining functions/args on the other hand, while Ida gives you a raw text box it just doesn't let you change some things? There I prefer the way ghidra does it, I especially like it showing what registers each arg is assigned to.

Another big difference I've noticed between the two is ghidra seems to operate on more of a push model, while Ida is more of a pull model - i.e. when you make a change, ghidra tends to hang for a second propagating it to everything referencing it, while Ida tries pulling the latest version when you look at the reference? I have no idea if this is how they actually work internally, it's just what it feels like. Ida's pull model is a lot more responsive on a large exe, however multiple times I've had some decomp not update after editing one of the functions it called.

Overall, I find Ida's probably slightly better. I'm not about to pay for Ida pro though, and I'm really uneasy about how it uploads all my executables to do decomp. While at the same time, ghidra is proper FOSS, and gives comparable results (for small executables). So I'll probably stick with ghidra where I can.