Technically, All subserver 1 has the most people. Like Leo 1, Taurus 1, Scorpio 1 and etc. As for transferring your character to another server, as nivle said it no just cost real money it costs a lot of money. If your character is a non RB or you don't have millions of gold and/or IM stuff then its not worth transferring it to another server. Unless you don't care about the real money problems then go ahead lol
Links to important stuff:
Transport Quests: http://wlodb.com/topics/99
WLO Pets: http://wlodb.com/topics/13670
WLO Emoticons: http://wlodb.com/topics/6195
PSN :)
TAURUS SERVER (NOT UPDATED - NO LONGER PLAY)
DRAGON CAVE - Click or see them if u will lol ^^