MMOs are an odd thing, not too many people will play more than one at a time. They're very time consuming and require a lot of commitment. People just find the one they like and stick with it, usually.
I played WoW for 7 years (I still play a tiny bit), most of my guild transferred to SWTOR and most of them have stayed there and have no desire to return to WoW. A few were unable to get a solid Operation spot and drifted off, which I blame ourselves for not pushing the 16-mans enough. I have watched some videos on GW 2 and frankly it doesn't interest me in the slightest, but I hope it'll be the game you're looking for.