The lights are on
Planetside 2 is my go to game, though it doesn't do it for everyone.
Team Fortress 2 is still one of the best tournament shooters on the market
Then you have your LoL DotA 2 and all the spinoffs from that, I would recommend LoL
Tera is going F2P next month I think, this is a full blown AAA MMO with a unique combat that sets it apart from games like GW2 and WoW. I know I am going to check it out.
Finally If you like Star Wars, Star Trek, or Lord of the rings all 3 of those are F2P