Ok so im not sure which to get next donkey kong TF or mario bros U. Which is better game and why? Its for a family to play 2-3 players at a time. We enjoyed 3d world and rayman legends so wanna get another good family game to play through. Any help apprecaited cos I have watch videos and read reviews but still not sure 

They both are good games. I'm going to leave that up to you.

DK is the better game in my opinion

I'm not sure if tropical freeze even has multiplayer. I would go with Mario bros U just to be safe.

It does.

Unless you didn't mean multiplayer, in that cause tropical freeze looks better in my opinion, but only slightly.

DK is 2 players max and hard as hell
Mario has 4 players and more family friendly

He did say 2-3 people though. It can only have 2 people. 

NSMBU, it's better for families. DK is only co-op. If someone isn't that good they can make platforms with the gamepad with NSMBU. You even have the new challenge games with a bonus co-op section.

I can't really speak for Tropical Freeze since I don't have it, but NSMBU is a pretty fun game! I think you should get it!