So... what's the best mastodon server to join as a new user?

I just downloaded the app to see what's all the hype about, and once again, I'm asked to pick a group, in this case, a server.

I suppose it's like Lemmy instances, so, is there a general one, or an equivalent of lemmy.world in terms of size, interaction, and so on?

My mistake if I'm understanding things wrong, thanks!