Guild Wars 2 is fantastic. An enormous world with numerous factions, great PVP, a strong personal story that can be soloed right up until the final boss, but encouraging you to organically meet up with other players with dynamic events and enormous collaborative battles. What's more, it can be yours for a ridiculous £8.79 this weekend (from Saturday January 24th), and it's buy to play!
That's right. No subs. Just £8.75 and you're in, forever. Thanks to Just Wondering @ HUKD, and to @DelTorro on Twitter for clarifying the start date!
As someone who still logs in from time to time (look out for Byssk on the Desolation server!), I'd definitely suggest picking this up. The amount of entertaiment you'll get, even solo, is insane.