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The Nikon viewfinder is better, especially if you match your finder to your needs, either the HP finder if you wear glasses or the non-HP finder if you don't. The F3's finder is brighter than the OM2's, but has less magnification, particularly the lower-magnification HP finder. Personally I've not been impressed by the OM finders after owning an OM1 and an OM4T, they're big but not terribly bright and the focusing screens are poor (note I had 1 screens, not the better but rare & expensive 2 screens).
However the Oly's metering display is significantly better, the F3 has a lousy LCD.
Personally, I'd look at a Nikon FE2 or FM3a if I was looking for a Nikon aperture priority body, they're smaller, have a better shutter (1/4000 and 1/250 sync vs the F3's 1/2000 and 1/80 sync) and have a much better metering readout, and they support standard Nikon TTL flashes. FE2's are also generally a fair bit cheaper than either the OM2 or the F3. If you put an FM3a screen in an FE2 it'll beat the pants off most other options and the FM3a screens are still available new from B&H for ~$35.
Oh, and skip the Nikkor 50/1.4, get either the f2, the non-pancake 1.8 or spend the extra and get a 1.2, Zeiss ZF or a Nokton 58 instead, the 50/1.4 is the weakest of Nikon's 50's IMHO.