Well, Technically I think the 28 is a better lens. Technically, its sharper, has lower vignetting, is better in back lit, better wide open.
But, you may just like the 24 with the sharp center, stronger vignetting, more back-lit flare and ghosting. I do, which is why I shoot both.
The answer is obvious to me:
Technically, you should have both. 🙂
If I had to choose one, based on Technical criteria, I would choose the 28. No doubt.
The 24 f/2 is an interesting lens, but I probably wouldn't replace it, in fact I had 2 and kept the better one. 28 f/2 would # 2 or 3 on the list if I ever had to rebuild a Nikkor system, and in fact I have a backup for the 28 I think its that important to my work.
If you can, try both at the same time and see how the behave in your style of shooting. If you want the Technically Best 28 for MF Nikkors then get the 28mm 2.8 Ais and put it on a tripod at f/8 and be done with it. Technically, the f/2 and f/2.8 are really very close in the performance you outlined above, the optical formulas are quite similar and IMO the 2.8 is a slower but sharper f/2 that focusses closer and is cheaper. SO, if you need the stop and need the technically Better lens between the 24 and 28, the answer is the 28.