I prefer Guild Wars. It's a one time subscription fee that's getting lower over time. Currently, you can spend $20 to get the core game. I own all of campaigns and play them like a casual game. I don't want xp, material, or gold grinding. I want a compelling environment and story that doesn't hold me back because I didn't reach level X.
Besides, I tried WoW and didn't like it. I like Blizzard. I love the Diablo series (mostly because it was unapologetic about being hack and slash, though I'm usually a fan of hack and slash). I thought WC was ok, and SC was pretty darn cool. I can't wait for D3; that's gonna be awesome.
BTW: GW just celebrated 4 years, updated tons of content (though I'm concerned about the rather large "micro" payments for some of it), and have surpassed 6 million units sold. I don't know how that translates into active players though. Plus, they just went live on Steam with all three main campaigns for $50.
Just my $.02 (the non Verizon math 2 cents).