I'm gonna say TF2. Why? Because, i've always felt like shooting people is better than buildin'. I mean, sure it's fun to build, craft and make stuff happen, but TF2 got that humor style that Minecraft lacks. Also, setting people on fire and then smacking them with a postbin for a double two hit combo is one of the best ways to fight. Always.
I don't even see how you can compare two completely different games, but ok. Minecraft i guess. It's more fun to play when i'm absolutely bored out of my mind. ~Moved to Games~
Wow...It's like trying to choose between children... But, TF2... Sorry! Minecraft is awesome and all but Valve has made something that constantly evolves and changes over the years it's been out to constantly make me want to come back and see just what that new piece of kit can do. I'm hooked and Man Vs. Machine has made sure I'm hooked all over again with it's upgrades. Now I not only have to consider what new kit can do for me in normal games but what it could mean in MvM too. And I like the strategy element of an already decent shooter. Minecraft is awesome but I do find I can become distracted away from it rather easily. I do enjoy it and wish to see the mod community continue as there are few creative communities I would defend to the hilt as amazingly awesome powerhouses of creativity but I'm not as invested in Minecraft as I am in TF2. Having said that, I am considering seeing if I can go jump into that Minecraft server I saw somewhere around here...
Team Fortress Bronies, unite! Minecraft is cool and all, but I've racked up more hours on TF2 than most other games.
Minecraft 1.8.3+ has been going downhill. TF2, 5 odd years old, it's stayed as good as it was when the Uber Update came out. You just ignore the F2Ps and count them as free kills. And it's... better.