I like armor, which actually represents armor, that means, which is designed with function in mind first. The fancy sets all look artificial and not useful except Manticore set, Bear set and of course Viper set. Sure thing they are my favorite sets just by looks. Although with Bear set I always feel like Geralt is overdressed in every situation (and should be sweating wuite a bit, yak.!).
Of all the other available armors I favor the simple medieval style the most:
Oathbbreaker/Thyssen armor (goes well with Mahakam trousers, imho)
DLC Nilfgaard set
DLC Temerian set
Right now, my Geralt is wearing GM Feline armor, GM Griffon gloves + boots, GM Wolf trousers for build purposes (changing swords unlocks always 3 item set bonuses of Griffon, Cat and Wolf if I want to, Wolf being the most used atm), all dyed black. Main swords are GM wolven swords. And with all the red leather dips here and there it gives a nice look. Sword sheaths fit as well.
DLC Undvik set
Order of The Flaming Rose set (does anyone know, if you can get the trousers and boots for it? I haven't found a diagram for trousers and boots, feels strange.
Touissant Knight/Tourney set
p.s.: wished we could dye all armors not witcher gear only. I am sure some of the stuff looked even better than Viper/Warrior's jacket design.