This is all based upon personal opinion.

1.- Durge

He's a freaking monster. I like that.

2.- Fay

Fair and powerful, known for maybe not carrying a lightsaber.

3.- ARC-77 A.K.A. Fordo

He might as well be my favorite clone.

4.- Shira Brie A.K.A. Lumiya

Imagine her being part of the Knights of Ren and dueling Rey.

5.- K'Kruhk

He was apparently dead after being defeated by Grievous, but NO, he survived!