A server advertising 100 slots with two people on it is a server that will be gone in a month, and your base with it. Sort by players and look at what is full on a weekday evening in your own timezone — this list is live, so that number is real.
x1–x5 is a game about logistics and breeding lines. x25 and up is a game about bosses and PvP, where a tame is an afternoon rather than a week. Neither is better; picking the wrong one is why people quit a server in three days.
Clustered servers let you take creatures between maps through an obelisk. One map on its own caps what you can breed and which bosses you can fight, so a cluster is usually worth more than a higher rate.
A heavy overhaul — Primal Fear, Omega, Eternal — changes every stat, tame and drop on the server, so base-game numbers stop applying. Filter for the overhaul you want to play, then read its own pages here before you join.
No tips here yet — be the first survivor to leave one.
Leaving tips is for survivors on the rewards list — reserve your rewards with your e-mail once and the form unlocks everywhere.