I have been playing Americas Army for the past 3 years.
It's a free download and it does not cost anything to play. (Unless you run a server) It's the only online game that I play.
I would play WOW, except I am not going to dish out cash every month to play. The guys at Blizzard must be zillionairs by now, 7 Million+ users at $15 a month. They have a license to print money.