I just want Super Metroid, Metroid II, and the original Metroid to be reiterated with true 3D environments, and for them to have good musical remixes (I wasn't pleased with the Other M at all.).
I would pay for an updated remake of
Super. Give it the controls of the GBA games (no separate button for running, a system where missiles are armed by holding a button instead of toggling them on and off, etc.) but keep the physics true to the original - otherwise the levels would have to be changed around quite a bit.
In addition, I would want more in-game options, such as variable difficulty settings (all available from the start, please)... and going back to the controls thing, the ability to switch between
Super's, with the run button and the weapon toggle; and
Fusion's/
Zero Mission's, with the streamlining.
Another thing to include would be a sizable extras section, in which you can view the endings you've unlocked, enjoy concept art, cutscenes, best times, and a sound test (which would include both the updated tracks that one hears in-game and the classic music); but what would really sell the game for a lot of people would be the inclusion of the original
Super Metroid as an unlockable bonus.