well if i can offer an honest and complete feedback, for BG seems more active Outland and with shorted queue (Ally Icrcrown queue are **** guaranteed), but Icecrown have also Wgasp (infestated by mboxer and ofetn unplayable) and 4x the population.
Also Icecrown have Sholazar basin and Icecrown that are basically in perma WPVP mode, still is a gankfest more then anything funny or interesting.
PVP Much more enjoyable on outland by my taste, more balanced, less mboxer and ppl tend to play a little better then the Donor ****** party that are Icecrown bgs