Guild wars is great. It's sort of set up like diablo2 in that you play on a map with only 2-8 people at a time and the monsters don't come back after you kill them. You don't have the typical MMORPG problems like kill/loot stealers, PKers, camping, etc.. But then again it seems less like a MMORPG because of that.
If you like to be involved with guilds, guild tournaments, and general multiplayer, you can spend a lot of time in guild wars. Also, if you just want to play occasionally and treat it like a single-player RPG, that's also possible, since there's not really a level-race where you're trying to catch up with your friends. You can get to the maximum level about half-way into the storyline, so I'd say the game is mainly about playing and not leveling.
WoW is definetly better as far as MMORPG's go, but guild wars is worth a try. If low on cash, you can typically find it used for around $30.