Analogue Stick >>> Circle Pad.
Stronger, wider movement range so can be precise, will last longer, circle pad feels very spring loaded and not as hardy. It also doesn't follow the curve of your thumb as well (movement wise) as much as an analogue stick does. They are good, but I prefer an analogue stick, though I guess I'll need more games with the circle pad as I tend to play with the D-Pad on my 3DS as the majority of games are fighters.
I would also prefer smash bros on the WiiU with a second analogue stick as I do smash attacks with the C stick usually, and only use the regular one for charge, though I guess it wouldn't take too long to get used to.
I'm also guessing they have gone with circle pads to keep the form factor slim for, say, two player tablet based games. I like the circle pads, but regular analogue sticks are much more precise, circle pad feels far too twitch for my opinion due to the strength of the spring.
We won't see smash bros for another two years I guess at least. Unless Sakurai sells his soul and can come up with the game in a little over a year! Look at the development time for brawl!
( Edited 08.06.2011 22:34 by Echoes221 )