I notice, that almost every helmet I have, be it the whiterun guard helmet, misc helmets like iron/steel/elven/etc, every single helmet is being shown as the best helmet, even though when I mouse-over it, it clearly shows on AR (-XX) Is there any reasoning to this?

Do you not usually wear a helmet? because if you're not wearing one, then anything would be better...

I'm always wearing a helmet, and it's usually a quite decent helmet, but the point is, even helmets which are a ton lower in level, such as a whiterun's guard helmet, while I'm wearing a daedric helmet shows up as the "best" helmet, which is quite strange imo. And it should be if it's in either the target or player's inventory, not whether it's being worn or not, but yes, I always wear my helmet.

I don't know then. Maybe someone else will have an answer for you?

Do you have any of the perks that require the same armor or type of armor and your preferred helm is different?

Ahh.. Good thinking!