I'm not a huge fan of either but Ryuryu does have considerably more potential than poor Cloris. All mama witch has going for her is brute killing power under skill--her base stats are poor and witches are too pokey to get much use out of assassinate--and that's undermined a lot by being so much harder to perfect than the alternatives. Meanwhile Ryuryu gets attack speed buffs from her AW ability and her Awakened Skill, a trait which is pretty valuable for a unit that is already inherently ignoring defense. The range penalty can be a real bummer, but her skill patches it up so it can be managed with some care.