Mithra by far. If the two baddies Set and Zath are not working together at least, but Mitras powers when used are really over the top from linghtning strikes to freaking meteors. Not to mention that he is the sun and can burn you to crisps. And he can give his priests the power to oneshot everything -.-

Zath can be a real bad god to mess with, since his power comes in unending swarms of spiders summoned by his priests. However, kill the priest and the mess ends.

Set is an idiot to be fair. He is the “head through the wall” kind, who may scheme but has no sense of tactics whatsoever, resulting in his plans often failing royally. I dont know how this guy ever got so strong to rule the exile lands through the ancient civilization. (Maybe because Mithra was not there and Set might be the only god who was worshiped that time. Or maybe Set just revels in dooming mankind, don’t know.)

Jhebbal Sagg is powerfull when his opponents can be mauled by alpha hyenas else not so much.

Ymir has giants under his belt and is knowing for mobilizing great armies when needed. Which can be a powerful force as well. He does not act often though. I dont know if he generally can beat Mitra, but if his cult is well established, he can.

Derketo is the weakest. She can be aggrissive when getting on her bad side with posioning food and whatnot but is the first to fall when some god goes on a rampage against the others.

Yog is an oppurtunist who eats all day and strikes when he thinks he has a chance but beside being worshiped by the darfari, he does not involve himself very much.