Why do you want the most populated server anyway? That leads to issues with things like overcrowding and mass competition for mobs, and folks flocking to those servers also means others become underpopulated, with known issues. As it stands currently, I don't think you'll have an issue finding a free company to join and folks to run FATEs with (And those are the main two benefits of a population on a server) on any server, so just pick one at random.

Oh, and I believe all the NA/EU servers are PST actually. There's just the two data centers.