I'll start off by saying a large part of my positive experience with WoW isn't the game itself, but the people I play it with. Honestly if it came down to the game standing on its own, I'd drop it in a heartbeat. But being in a guild filled with people I know from real life really adds to the experience. I bought Rift when it came out and had only one other friend to play it with. I think I got to around 35-40ish (If I remember right) and ultimately decided that while it was really cool, and had some interesting features, it wasn't different enough from WoW to make me want to pay another subscription fee. Especially when you factor in friends, time already invested into WoW, $$$, ect.
I never had the chance to experience raids (Other then large-scale outdoor rift events/bosses) so I can't really compare there, but I will say there are some pretty good ones in WoW (Kara, Ulduar, Ect).