anime recommendations for my friend

I'd recommend Soul Eater. It has characters tu can easily care about and great villains. It has boys and girls working together to slay witches, but there's no real romance.

If I can make any recommendations I possibly suggest Fairy Tail, Code Geass R2, Spiral: The Bonds of Reasoning, inuyasha The Final Act, o Buso Renkin.

Well upon hearing 'no romance' (unless tu count Yagami's manipulating of Misa Amane as romance), good villains, an interesting plotline and good characters I instantly thought of Death Note. Whether it's the sort of thing she would like I'm not sure, but I certainly enjoyed the manga and am working my way through the anime, and I thought it ticked all those boxes.

I don't know if your friend will like them, but I'll try to lista a few different anime that I think might meet the criteria.

Claymore
A Certain Scientific Railgun
Puella Magi Madoka Magika
Darker Than Black

That's all I can really think of. Most of them are a bit dark, but, since plot is important I didn't pick slice of life. I also left out ecchi and tu dicho no romance, so that limited what I could think to recommend.