Here's my amazing wish list.
I'd like to be able to customize my armor's paint job:
Head primary, head secondary, head detail, chest plate primary, chest plate secondary, upper arm primary, upper arm secondary, forearm primary, forearm detail, gauntlet primary, upper legs primary, upper legs secondary, kneecaps, calf primary, calf secondary, boot primary, boot detail.
Also a "battle scar" option that lets you make your armor all destroyed in different parts with different kinds of scaring possibilities:
Head (left, right), chest plate (top left, top right, bottom left, bottom right), arms (top left, top right, lower left, lower right), legs (top left, top right, bottom left, bottom right), boots (left, right).
The ability to transfer all armor gained in Halo 3s multiplayer over to Reach (unless they can be unlocked in Reach as well). Also, lots more armor permutations such as:
SPI armor like in GoO, Mark IV like in Halo Wars, Those are all the ones I can think of now, but there are many more. Also, Elite armor (if available in game) should have as many -if not more- armor permutations than the Spartans.
Anyway that's my 2869 cents, I realize that this is a tall order, but it's basically everything I would want the game to have in terms of armor customization. Peace.
~Hunter