Litchi is really good but you have to rely on placement of her staff and relation to you and the opponent to use her effectively. I am slowly improving with her but it takes a lot of work.
I like a challenge! Fighting games for me are about growing as a player and challenging oneself. Therefore I use her. Noel is interesting. I also like Jin and Tsubaki.
Lol, well you do use Lisa and Leixia as well (3 L's O_O). You never make things easy on your self xD. Jin is good, and Tsubaki is decent if I'm not mistaken. Noel's my waifu.
Ayane is incredibly difficult but is worth every second spent in the lab. Your Leixia has gotten a lot better and will only improve in the future. NM is moderate but requires a lot of patience to handle properly. Litchi is harder than all these characters though. You can always try out Izayoi if you want.
Izayoi interests me too. I think I'll try her out some more. I really don't know yet. I've only scratched the surface of the game. Imo its one of the best 2D fighters out there along with SF and GG.