This is a hard one to answer because there are so many, so I will divide it by class,
Warlock
Mage
Priest
Rogue (with a red bandana
Druid
Monk
Demon Hunter
I have yet to find a set I like
Hunter
https://www.wowhead.com/transmog-set=2233/eagletalon-battlegear-raid-finder-recolor
Shaman
Warrior
Death Knight
Paladin
I also love the Arathi sets, all of them, and all of the Horde side Darkshore sets.