I recently watched Big Hero 6 and I immediately like Baymax, a robot invented to be a personal healthcare companion. The film is indeed funny and the robot's ballooney appearance made it more adorable. I think the idea of the robot’s appearance and abilities is cool, and it surely added humour to the story. Meanwhile, How To Train Your Dragon2 is also hilarious. The story had a wonderful twist, plus, the graphics is wonderful, and I believe it would look awesome if you watch it with 3D.
Both films are definitely entertaining, funny with a bit of drama. Both are nominated for the Academy Award, and they both deserve it, but I believe How To Train Your Dragon2 has a better shot for the Best Animated Film.