Warhammer will give you amazing damage and a great knockdown rate, but is rather short. It is the best if you can manage to get behind or inside the enemy formation.
I enjoy short weapons with either very high damage or speed with my soon-to-be 30-15 build. I use a MW short nordic war sword, MW warhammer, or MW one-handed battle axe. Often 2 at once for different situations.
If you need length, the scimitar or elite scimitar (i prefer the former) are very valid choices, as well as the chinese swords including the lieuyadao or whatever it's called.