My Top Priority Change would be, unlike Halo 5, Quality over Quantity. From this 230-ish Armors I would throw 200 or more out of the Window. (if they would be going to make a Return anyway...)
I would make them less Shiney and plastic and more like Halo: Reach.. Grittier and stuff.. And I surely wouldn't implement them in ReqPacks.
So. In case of Customization:
- Add-ons would be great
- Maybe with changeable Knifes and Knife Positions, Shotgunshells and other Gimmicks as Add-ons, if they are not integrated in the Armor somehow. Don't overdo it, that u can have like 100 Bullets across your Chest, keep it simple.
HuD (Throw some Custom HUD Options in, like in the Campaign.. ^^)
Black or Custom Undersuits. I don't mean the Colours by Custom.. They should be Black, but I mean Patterns, like the Chars from the Campaign. That would be a little, but great Addition.
I'm all for the Armor Effects.. But if you implement them, make them harder to obtain.. Maybe, instead of only an Emblem, you could give them out, if you reach some of the Highest Ranks, alongside some Special Armor here and there..
Or you make them really expensive, if this System has a Chance to return.
And, if there are going to be playable Elites in Infinite.. Give them some love, too. Throw everything from Halo CEA to Halo 5 Guardians and Halo Wars 2 in, what we have seen (Games), alongside some new Armor, and we would have like 25 or 30 Armors for Elites.. It would be -Yoinking!- great!
Yeah, that would be my 5 Cents to it.. :'D ^^