I think a lot of people are just tired with WoW in general and only keep playing as their friends are there which is sometimes why new games find it hard to retain subscribers. New content in MoP will bring some back, but when they realise half their friends are gone and they are carrying rude randoms in LFR etc they will leave again.
People bitch and moan about SWTOR but it's actually a pretty fun game. I'm really looking forward to the new OP and warzone. I'm happy to stay (and subscribe) and on the off nights I can knock over some single player games that I've been neglecting. So far I've really enjoyed all of the content they have added and I really rate KUS and LI as two of the best dungeons I've done in any MMO. Another positive is that they added APAC servers so that I can get decent ping (less than 10 instead of 150-200 in other games) and it makes a huge difference to the enjoyment.