Let's look at this practically:
You already have a D300 and an X700.
That rules out the Olympus, unless you're a gearhead looking for a fix (sorry guys). With your two systems, there's really no logical reason you can't find something you like that will work with whatever you have already.
Now, what lenses do you have for your other systems? That would be the deciding factor. Do you have an non-DX, non-G lenses for your Nikon? What Minolta lenses do you have?
BTW, if you go with a Nikon, I'd go with a 50/1.8 or 50/2 of any variation. They are all very nice and probably a tad sharper than the 50/1.4, which I've never had much luck with. They're also cheaper (in the case of the Series E about 1/5th the price). Pick the 0.2m-focusing 28/2.8 (I also like the 28/3.5) or a 24mm to go with it. Between those two lenses, the cost difference is mostly gone (still a little more, probably, but much less).
The F3 was the pinnacle of pro-grade manual focus SLRs... It was in production for 20 years, many hundreds of thousands were made, you can still get parts, it's relatively easy to work, there are hundreds of accessories and extremely solid. No other single SLR model can say the same thing.
Besides, the Nikon F-series cameras are like AR-15s or Legos. You want it to fulfill a specific task, you can do it.
