3D easily.

2D. Or third-person 3D

Definitely 3D - that's the only way for metroid to stay relevant - best would be to add a multiplayer campagne

We need a 2D Metroid more than a 3D one. The last 2D Metroid was on the GBA, the last 3D Metroid on the Wii, it's been longer since the last 2D Metroid.

Why not both ?

To revamp the franchise I think we need a 3D installment though I wouldn't complain if they released a 2D one

It doesn't matter, as long Sakamoto's not in charge of the project, both options will be fine.

Definitely 3D. I liked Super Metroid, but the Prime series is unmatched. Especially with today's graphics the game would benefit more if it's a 3D game

2d i dont want any more primes i am not a fan or fps but if the let you choose in one game that would be great

I'd like to see a 2D one as well, but I've got to say that I want the Metroid games to become one of Nintendo's biggest franchise and that's impossible if they would go with a old-school style. Furthermore, Nintendo needs more big and epic 3D games, they have enough 2D games

Both if possible, but it's been a while since a 2D Metroid, so I guess it would be cool to see that!