Gambeson, easily. It takes almost no effort to make relative to anything else, the downsides are almost nothing relative to anything else, and upgrading from it has minimal benefit. Armour is painfully unbalanced, and without mods to reduce the downsides I don't even bother making it.
I find the class system pretty inconsequential and uninteresting. I think it would be more fun if everyone started out the same, with a system that allows you to pick whatever traits / malus you want after gaining enough experience, basically building your own class.