Halo 5's Argonaut is pretty decent. Well, the helmet at least. I wouldn't mind having the set back if it means they make the actual armour more unique, since armour in Halo 5 tends to look very similar. That, or it is very difficult to notice any differences.
Someone mentioned this one already, but I also want Security to return, with either design, as long as the Halo 3 one doesn't look like Halo 5. It wasn't necessarily bad in 5, but something looked off about it.
I found that most of the Halo 5 armors, especially FOTUS, to be really really ugly. No offense. I know they'll be coming back most likely, but I'd like a bigger focus on the older armors getting a facelift before they think about dumping the 5 ones in.
I also agree that Fotus isn't really all that great. The helmet is
undeniably unique, though! Maybe if the set's colour distribution or whatever was better? I have it in 5, but I don't use it. I could never find a colour scheme I liked on the armour. Too many of 5's colours don't look very good on some armours, nor do they look different enough from other colours, but I believe that is because of the game's art/visual style or something.
Edit: there is kind of a recent thread for this already, maybe we should have all posted there...does this forum have a 'thread merging' function?