That might seem an odd thing to ask given we're still months away from the game's release, but thanks to the fact Ubisoft showed the same level at E3 on the two consoles, we can actually get a good look at how the Wii U is shaping up as far as multiplatform titles go.
And...well, call it personal preference if you like, but the Wii U version wins this one for me, mostly due to the improved lighting. Though, you know, you'd expect that, given the console it's up against was released in 2006.
You can check them out below. The Wii U is on the left, PS3 on the right (if you click the "YouTube Doubler" link underneath you'll be able to see both demos running side-by-side).