The CCPro is really weird with its diamond layout. It isn't like a square, it is more like a rhombus.
The Wii U Pro Controller and the 3DS doesn't have that problem.
Grips.
I've become accustomed to the layout, but it needs to be adjusted. I feel the XBO controller might be good though since the sticks feel nicer. Haven't had much time with the face buttons to say much about it.
The Wii U Pro Controller and the 3DS doesn't have that problem.

Stick > Circle PadOutside of the lack of a second set of triggers and a second analog stick (both of which combined might make throwing things awkward), how would the 3DS version control worse than the Wii U version would?
Grips.
I hate it (360 controller) for Smash since the sticks and buttons are too stiff for something as fast-paced as Smash. The sticks are also slightly more raised which is a problem.I wonder how playing Smash would be on a 360 / XBO controller. The 360 controller (don't have an XBO so I can't say) is my favorite controller ever, the only thing that competes is the GCN controller and that's just for Smash.
I've become accustomed to the layout, but it needs to be adjusted. I feel the XBO controller might be good though since the sticks feel nicer. Haven't had much time with the face buttons to say much about it.