It only really matters for the “local” feed which instance you choose. I don’t really see much point to that one honestly, except if you’re on something like startrek.website where “local” is “show me all star trek stuff”, or something similar.

And yes, it is important to spread out the user base across multiple servers and not all end up on lemmy.world.

So I’d say find some smaller instance, maybe with a community actually physically local to you, and make that your main one. Or don’t and stay on lemmy.world, I’m not your dad.

Perpetual plug to my userscript which changes all links to point to your home instance to make this even easier :)