What do you mean in terms of "busy" like, most people, most economical, most whatever? Just a bit confused.
Smp9 tends to have the most people as I see it, but smp1 seems to be the server besides smp5 that holds the most events...
that's not possible at the moment, as other people have said in your other thread... Sorry, only way is manual labor You lose everything, and there is no way to move builds cross server, but you can move items with vault.
Smp2 barely has anyone connected, it is a "home" server, and also smp3 is the server of the economy. Smp7 and 9 are flooded with outposts and new players, and smp1 is always busy, as it is the "main" EMC server. The rest are normal.
I would say that smp1 generally has the most players at most times, but at peak times smp9 does sometimes take over
Mostly because of new members population (maybe they are more casual than older members) and outposts, and drop parties