Rudra, 10 rudras. Amaterasu/Sol is nice, but Rudra is much, much better. Rest is garbage. Graz, i can't roll Rudra with 400+ tries.
Edit: What lineup? with Rudra - any water hime, even R for begining. Sol/Ama - it can be almost any element, Sol fits everywhere, especialy awaken sol, Ama can be off-element support too for beginning - regen, def buff, SS. So look at other himes, choose strongest element and play with it - you have very flexible couple.