most populated server?

[Nici]

Just look for the server that is always closed and you can't create a new character on....like ever lol...which that would be Balmung.

[Dement]

I found a site which indicated Balmung had about 24.5k and Gilgamesh had about 17.2k and they were indeed the most populated servers. I don't know how precise it was, the site appeared to be created by the Japanese so I can't really tell exactly how they're coming up with the numbers. Either way, take it with a grain of salt.