I chose the Vita version. From the reviews I've read, the controls feel more intuitive on the Vita because they take advantage of the touch screen for looting and other actions. The PS3 version has to use the right analog stick which they say feels a bit clunky. I'll probably still pick up the PS3 version later, though.
This type of game just feels like a good one to have on the go. I don't play a lot of local co-op these days, so just having online co-op is fine. I can live with the smaller screen because the Vita's OLED screen is gorgeous and I'm sure it will really make the graphics stand out. Plus, supporting this game on the Vita will hopefully mean more original titles coming to the platform.
It seems like a lot of people are picking this up on the PS3 for the bigger screen. I got it for my Vita though (Hooray!)! So many people are bashing Vita :-(. Vita really is a fantastic device that needs and deserves a lot more love than people and developers are giving it!! I am super stoked to play Dragon's Crown on my Vita though, should be great!
Was going to pick this up for Vita first, but heard from TotalBiscuit that the framerate tends to get a bit choppy in larger battles. I assume I'm eventually going to pick up the Vita version further down the line since the game allows you to transfer save files between the PS3 and the Vita.
Vita. Haven't had any framerate issues. Looks just as pretty and is portable. Touch screen works well, I've tried using runes and getting hidden treasures with the right analog and it's SUPER annoying.
I went for the Vita version, and I can say that I am loving this game. I haven't had any issues with this version whatsoever. Though I do plan on eventually getting the PS3 version to play with my brother since he doesn't have a Vita.