Mine is Faraam from ds2. There's something about the ds2 vibe and aesthetic that I find so appealing. Also this armour just looks so good.
Runner up is fallen knight set from ds3 cos it looked really cool when embered and Lautrecs from ds1 cos bronz. Fluted set from demons is also very good.
In Dark Souls 2 I really like the Falconer Set for its looks and the Tattered Cloth for its utility and coloration. In DS3 I switched between Fire Witch and Firekeeper, with a lot of mix and matching on other armors. Edit: How the hell did I forget the Cathedral Knight set? I farmed for that like crazy, then realized I didn't have the stats to wear that and not fat-roll. And still wore if, because it looks nice and I'm stubborn.