Well, both of them at MLB are still Fire characters' ATK↑ 40% / HP↑ 20% so not really "every" way, but yeah, Crom has about 200ish higher stats.
Both summons aren't really THE best. Double ATK down to enemy from Crom, and a pathetic 3500 DoT from Cthugha... I guess the double ATK is better?
Depends if you have anyone with intercept/taunt, like Argos for example for fire, making it more useful for enemy to be able to combo attack so she can return even more DMG back.