Aesthetically, the Barbarian and Desert Voe sets are my favourite.
As far as usefulness goes though, the Phantom Ganon Armour is arguably the best combat-wise (or the Radiant set but I don't like the way it looks) since the bone attack bonus is stackable with Attack-up food and gibdo bones are OP.
Both the Froggy and Dive sets are excellent additions that are incredibly useful. I love the dive set in particular because gliding with it is a ton of fun.