When I got my BM 806D2, 921, 940, and 941, I instantly fell in love with the 921, and thought it was the perfect utility knife. I wasn't too pleased with the feel of the 806 in my hand, and wasn't impressed with the factory edge. I also liked both 94x, but find the 941 to be a better blade shape for general utility than the reverse tanto of the 940. I do like the 940 for show and tell though. Good feel in the hand, and the aluminum scales give good grip.
Well, as you use your knives more and more, first impressions usually change somewhat. While I still love the 921, it has been moved to a secondary position, while my 806D2 has moved to a primary position. The reason being I feel the 921 handle is too slippery, especially when your hands are really cold and dry from winter weather. This is really only a problem when opening and closing, not when using. Also, I have sharpened the 806D2 to the point that I'm extremely pleased with it's cutting ability now, and I'm really starting to like the feel of it in my hand.
Long story short, I originally preferred the 921 over the 94x over the 806D2 (which was primary SD EDC). Now I prefer the 806D2 for main EDC and SD, and will use the 921 and 94x models on a rotation basis for just light duty stuff.
Of course there is still the Large Classic Sebenza that is coming in that I won in the passaround.
Mike