Hm...
Well, first, I'll list my top five hopeful Melee and Brawl returning stages, then pick the best from those:
Melee:
1. Brinstar Depths. Even though everyone hates this stage, I can think of many reasons why it should be back. First off, Kraid isn't in the game at all! That needs to be fixed. Second, even if it's a bad stage, it'd be a really cool Omega stage. Finally, more Metroid music. How about Vs. Rundas?
2. Big Blue. WHERE IS IT? This was the best travelling stage and now it's gone. I blame the 3DS version.
3. Rainbow Cruise. I repeat, WHERE IS IT? This is one of my favorite stages and there's no reason for it to be gone either. I'd love if this time they gave this stage many Super Mario 64 tracks.
4. Great Bay. Majora's Mask represent. More Zelda music too. I wonder how Tingle would work though.
5. Princess Peach's Castle. Nothing much to say here, I just miss this stage.
Brawl:
1. Pirate Ship. My most wanted lost stage. The fact we have no Wind Waker stage is a travesty, especially when they had the perfect opportunity to update it to match the recent Wind Waker HD. WTF is it gone?
2. Shadow Moses Island. Obviously, Solid Snake included. But besides that, Shadow Moses is a great stage with AWESOME music, and I'd really like it and Snake to come back.
3. Mario Bros. This stage is terrible. And that's why it is a great stage, and I'd like to see it return. Plus, it represents Luigi's first game. That makes it special right?
4. Hanenbow. No joke, I love Hanenbow. My only complaint is no music options. Fix that and it's one of my favorite stages to **** around on.
5. New Pork City. Probably not going to happen because Lucas wasn't released with it and it's probably too much for the 3DS version, but despite it's gimmicks I did like this stage.
---
Now, for my overall Top Five:
1. Pirate Ship
2. Brinstar Depths
3. Big Blue
4. Shadow Moses Island
5. Mario Bros.