Demon forms demon mythic path

Hey guys, which demon forms do you use and why?

Especially regarding demonic form iv. It seems Balor is superior to everything. Why would you use Gallu for example? The only benefit of using Gallu is Falchion and if you specialize in it to have those big two-handed x3 crits on 15-20 (over 200 crits). More if you select two-handed subclass for fighter. Other than that, bonuses to strength etc are much lower.

Also, how exactly do aspects work? Are they completely passive? Do I benefit from all of them while in demonic rage? You have quite a lot of them bu the end after all.

On a side note, demon forms don’t give stuff specific to a given form. No resists, DR, SR, true seeing, at will abilities etc.