Maria is the first one I evolved too, she is just too cute
I think you could evolve your max level girls. For me the hardest part is getting them to max level in the first place. You can easily bring them back up to level 20 or so with the manyus you have lying around and makes for a huge difference in strength. Even if you don't have much money right now, if you stop feeding manyus and focus only on dragons and gold you can gather the necessary materials pretty quickly. Give the advanced daily a try, it's much easier than the ultimate mission.