My detergent preferene seems to always be in flux, but.....
The one I always appreciate is Tide w/Bleach powder, original scent. I have never washed darks with it, but P&G sure wants you to think you can.
If I could indulge and have TWO detergents, it would be the above mentioned Tide and liguid Cheer for Darks. That is my favorite combination.
Gordon