After playing since release my favorites are now as follows:
1. Tail gunner (filthy)
2. Cyborg (more of a tie with 1) (absurd Unbuffed damage, incredible/op skills).
3. Samurai (from now on I will refer to as "the war beast").
4. Pharaoh (probably the best of the group)
5. Soldier (honourable mention as he's my farming workhorse).