I'm not sure you can go wrong with any of Nikon's wide angle primes. I read bad things about the 28mm f/2.8D, but I when I got one to try a few years ago, it was fine. I believe my 24mm f/2.8 AI is the best lens I own, optically anyway. It has CRC, a 52mm filter thread, and can be reversed for macro.
I haven't tried the 20mm primes, but the f/4 and f/3.5 (new) versions are both tiny and accept 52mm filter threads as well.
I think you should make your decision based on the field of view you're after, rather than what people say about "bokeh" or "sharpness". Some people love ultrawides and some people avoid them. I belong to the former group; my 18mm is tied with my 50mm as my most used lens (the 18 I have is huge and hard to find though).
I should mention that it took me a long time to get used to using a wide angle; it's really hard at first.