The 55 1.2 is the worst of the bunch...but it is still good IMO. If you need f/1.2, you more than likely have more to worry about than extreme edge-to-edge sharpness and lack of aberrations. I love my Canon 55mm f/1.2 S.S.C., and it performs similarly to the Nikkor 55 f/1.2. I like it's ability to go "dreamy" and "shaky" when wide open. I have borrowed the Nikon 55 1.2 many times from a friend, but never bought one for myself, since it is pretty much exactly like my Canon lens I mentioned.

The 50mm f/1.2 AI-S (still sold brand spanking new for about $700) is notably "better." And once you stop down one stop, it is unbeaten by anything as fast and as affordable. Stop down past f/2.0, and it has no real advantage over the slower 50mm lenses.

The 58mm f/1.2 Noct-Nikkor is incredible at f/1.2. But they cost thousands of dollars. And once you start stopping down, you won't see a difference between it and the AI-S, except maybe that the AI-S will be a bit "better" at your everyday f stops. Not worth the money for a one-trick pony, IMO.

The 50mm AI-S is the best compromise in the world of Nikon f/1.2 lenses, the way I see it. You can get them new for $700, or used for $300 to $500 depending on condition. It is very good wide open, an as good or better than any other f/1.2 Nikkor when stopped down.

My comments above relate only to the 1.2 lenses. The best 50mm lens in terms of all-around optical performance is the 50mm f/1.8 AI (not AI-S, which I believe used the Series E optics), by far. The f/1.2 AI-S beats the f/1.8 AI up to and including f/2.0. Past f/2.0, there is no difference that I can tell, except that the f/1.8 has no distortion worthy of mentioning (and is much smaller and lighter). And it is also the cheapest. Go figure. But if you need f/1.2, you need f/1.2. Just think about whether you really need it before you pass on the sub-$100 50mm f/1.8 AI. My two cents. YMMV.

The 50mm f/1.4, while extremely popular, is kind of pointless IMO, given the choices on either side of it. It's optical performance is good, but not "stunning" like the f/1.8, and it does not give you that much more speed. It also can suffer from some focus shift at the wider apertures. That can kill you when shooting at close focusing distances. What good is a wide aperture if what you focused on doesn't come out in focus on the neg? This being said, if you come across one for cheap, go for it. They are fine all-around lenses, and they give you f/1.4 if you need it.

The 50mm f/2.0 lenses are nearly as good as the f/1.8 ones, and can be had super cheaply. This would be my recommendation for the best "dirt cheap" Nikon 50mm. This or a Series E.