D3 all the way for me. But that's just it. It's a personal thing. It's not a case of which is subjectively better than the other. If having the best physical keyboard ever on a smartphone is important to you, the D3 is the best phone in a long time.
I'll be all over the D4 when it comes out (in a year or 2) but until then, 4g is immature, saps the bejesus out of a battery and is spotty. In 2 years, it'll be great. Not there quite yet.
The D3 is an AMAZING piece of engineering and features the best keyboard ever. If you don't need it, and you"re willing to deal with 4G growing pains, go Bionic.
If you need a keyboard, like I do, than you would be nuts to pass up on the D3. AND for some reason, 3G seems to be MUCH faster on the D3 for whatever reason.