So it looks like the second best East Coast server for PVP is Helm of Graush. Most likely SWTOR will not let you transfer to Fatman, so this would be your next most populated right now. From information taken at www.torstatus.net
My personal opinion I think it would be more efficient for SWTOR to do server merges vs character transfers. Then there would be no need to make the "right" choice, to transfer your character to. Even better would be to cut the amount of servers down by server merges. Then allow character transfers, if you please.