The demons need to be reworked; the rest are fine, some are just good...
But the devils you mentioned as being the best – you're wrong. They are only good when summoned by the Lords, but they don't even come close to the crystalline, black, or lava angels, or the titans... And the cave lords and spawn – in my opinion, they are the only truly unique ones – especially because of the slashing swords and fireballs, which are quite helpful when you buy them!!!