In no particular order:
Tinkerer (Alchemist) - Cause gadgets
Archaelogist (Bard) - I like bards, but I also like the option to play a bard that replaces the performance stuff
Monk of the Four Winds (Monk) - Only like this one for the flavour, as it's a pre-Kineticist way to make an elemental bender
Sword-Devil (Ranger) - Bit of a cheat since it's from the comics, but I do like the idea of an agile hunter
Invulnerable Rager (Barbarian) - Cornerstone of so many fun builds