A lot of MMO's are going to have a lot of the same pretence as wow, but will never really live up to their expectations. It's really going to depend on what turns you on..
Some of the top F2P MMO's:
Star Wars the Old Republic (
http://www.swtor.com ) - If you like Starwars, you will probably like this game as well. It was pretty fun.
Archeage (
http://www.trionworlds.com/archeage/en/ ) - The newist one to be released. Also made by Trion
Defiance (
http://www.trionworlds.com/defiance/en/ ) - Game based with a TV show that it tries to match. Not bad
Tera (
http://tera.enmasse.com/ ) - Actually a pretty good game, one of the best F2P's I think. Lots going on in it and a pretty awesome community
Rift (
http://www.riftgame.com/en/ ) - Rift has been around for a while and is pretty neat also. Has a few expansions and is made by the same company that does Defiance (Trion)
Champions Online (
http://www.arcgames.com/en/games/champions-online )- If your into the super hero types.
Elder Scrolls Online (
http://www.elderscrollsonline.com/en-us ): It is not Free to play yet, but will be in March from my understanding. If you liked the Elder Scroll / Skyrim games, this is pretty much a MMO version of those.
I have characters on most of these, but I have the attention span of a Gnat. I play wow on occasion just to play the new content and to mess around with friends.