Unless you need the speed or the brighter viewfinder, I would go for an early H 50 2.0 non AI lens that's been AI'd (the later AI lenses have "better" coatings and don't image the same). Every time I look at photos made by mine I'm amazed at how good it is. Quite possibly the best 50 lens I've ever used, including Leica. The first shot is at f8, the second at f2.8. The last two pics demonstrate what I would call "excellent IQ". Not overly sharp or anything, just really nice imaging. Best $30 I ever spent (AND there was a Nikkormat FTn attached to it too).
I own the 50/1.2 AIS and it is exceptional (so good that it is one of the few manual focus F mount lenses still made by Nikon). However my impression of the older versions, including the old 55mm F1.2 non-AI, is that they are also very good performers for such fast lenses and bargains for what they are.
And regarding the F2 vs. F1.2 Nikon primes, I do not agree with momus. Although the slow Nikon primes are indeed fine lenses (see the excellent photos he posted above), the F1.2's will significantly enhance your opportunities for low ambient light photography if that is what you need. The reasons: they are very sharp wide open, and extremely sharp when stopped down just a bit. Many shots will be possible in room light with an F1.2 that are otherwise just impossible with an F2 prime - many frequent ambient light shooters have known this from experience for a long, long time!
Here a thread related to this subject from another site I frequent:
And regarding the F2 vs. F1.2 Nikon primes, I do not agree with the previous poster. Although the slow Nikon primes are indeed fine lenses (I speak from experience and the posters examples aptly illustrate this), the F1.2's will significantly enhance your opportunities for low ambient light photography if that is what you want. The reasons: they are very sharp wide open, and extremely sharp when stopped down just a bit. Many shots will be possible in room light with an F1.2 that are otherwise impossible with an F2 prime.
True enough, if you can accurately focus in such dim light especially with the razor thin DOF at f/1.2. I'd rather use an f/1.4 or even 2.0 and either a faster film or push a stop or two. But that's what works for me.
I recently got the 50mm 1.2 Ai-S and it's an amazing lens. I'm not selling the 50mm 1.8G AF-S, so I'll be using them in tandem whenever I need whatever lens.