Browse the previous pages a little bit. Its been discussed pretty thoroughly.
If you want the maximum damage output and long term use Bacara, Daisy, Sakura, Flowering Peach are very solid (included one from each type). However it depends on what you want from that girl.
There are some nieche abilities that make a girl very good despite her having lower stats (example 5* Toad Lili, not so much damage, but her healing passive is amazing).
Scroll Upside, hit the Units button. Look at all the 6* in each type, and then choose depeding on which combination of Stats/Abilities/ and looks does appeal to you the most.