To contrast. In a game like Quake you are only as good as your Rail-gun aim it's pure skills. Or StarCraft for that matter again skills based.
The advantages from these kind of games in combatting addiction is that they are hard to become good at. you can't just get powerleveled up the latter.
The skills stays with you, the same is not true in WoW.
Having seen a couple of friends dropping out of university for a year because of games like EverQuest and WoW my advice is:
Don't play games where it's the avatar that gains power. Only play games that makes you a better player.