Outland represent.

I started out on Sporeggar with multiboxing but felt that RP and multiboxing didn't go well together so moved to Emeriss, after some time I found that server mighty boring and transfered to Outland. Which has a superb community and good puggage too! It's a very crowded server so not advised if you really don't want to see 500ish queues at peaks, however. But for me it has been totally worth it.

There's at least one more multiboxer on Horde side (Agnoors) with me and at least one on alliance side as well (Funkstar) that I know off.