I say Sunshine 2. A sequel would be amazing. All the water effects and the particles in HD would look fantastic. Also I like how Sunshine had more exploration while Galaxy was pretty linear for the most part. The fact you could see the other areas in Sunshine was a great touch. I like Galaxy but theres already 2 of them and I love FLUDD. The music in Galaxy was beautiful but I'd take gameplay over music anyday. Also Sunshine had that awesome vacation music. They should have 2 players. Mario and Luigi. 4 would be too hectic for a full 3D Mario game. I'd also like a Sunshine remake but I'd rather have a sequel. Which would you have?

EDIT: To all the people saying something new, i'm saying in between these 2 games. I'd like something new instead as well, but don't say neither because its off topic. Between Sunshine 2 or Galaxy 3.                 not Sunshine 2, Galaxy 3, 64 2, or something new.

100% Mario Galaxy 3 cause I really didn't like Sunshine

Sunshine 2 of course.

Not enough Mario adventure games, they are the best

Lol neither thanks. Super Mario 64-2 please. Still the best 3D Mario Game

How about something new?

I'd even be satisfied with Sunshine HD.

That is an incredibly tough decision. Sunshine 2 edges it for a couple reasons. One, Galaxy had a sequel. Two, Mario 3D on Wii U isn't THAT far removed from Galaxy to me. Finally, I really enjoyed Sunshine and would love to revisit that world.

Well thats what we should all be expecting in 2016. SMG2 is the only sequel in the series and the only one to make 2 3D Marios on 1 console. WiiU deserves something new and epic of its own.

Sunshine 2. I know that people seem to be hating on it in retrospect these days but I loved how the whole world felt connected, and the FLUDD was simply fun to use and muck around with. Probably would be looked on more favorably these days if it had been a new IP and not followed Mario 64 I think,

Sunshine 2 by far. The tropical setting would look nothing short of amazing given the Wii U's hardware and dedicated developers.

Unfortunately though, it is the option that makes the least business sense.