I haven't seen either (don't really plan to watch How To Train Your Dragon - it's not the kind of animated movies I watch), but I'm going to say A&O4 just because it's from a franchise that I'm familiar with. (I haven't seen HTTYD.)

Alpha and omega all the way!!!!!

I loved both, but I saw HTTYD 2 twice in and theaters and it blew me away. I cried and laughed and honestly it obviously had a lot more put into it. Don't get me wrong though, I loved AAO 4.. but HTTYD 2 is my favorite movie next to the original AAO.

Haven't watched HTTYD 2 yet.

Why do you do this to me? Making me choose between two equally good movies. Actually wait, no, that would be choosing between Episode 9 and HTTYD 3.

Sorry. Httyd2 Is 10× Better.

Love HTTYD 2. It’s just as good as the first, and it’s leagues better than A&O 4.

Definitely. At This Point. A&O Is More Of A Guilty Pleasure Movie Than Any Thing Else.

I've never seen HTTYD2, but it logically CAN'T be worse than A&O4.

You really should try to watch it. It’s the closest that Dreamworks Animation has gotten to “grown up”.