At sometime I have used all the 'Pro' versions made by Nikon with the exception of the F5 (too heavy) and they were all, very good. Between the F2a's that I owned (3 or 4 - I forget) and the F3's (2 x F3hp) I would go for the F2a every time. It was as bomb proof as they get. It gave the impression that little short of a direct hit from a HE shell would stop it working. The F3 was probably technologically better, more advanced electronically. but gave me the impression of not being as robust.
I think that this can be supported by the numbers of F2 cameras still functioning perfectly over the number of F3 models. I don't know about the rest of the world, but for every F 3 models still working and working well in UK and for sale, you will find many more F2's (or for that matter, even the original 'F'.)
The F3 was a very good camera, but with hindsight, this appears to be almost a development stepping stone between the F2 and the F4 where Nikon looked at the longevity and endurance of the F3 electronics, then took the gloves off and made the F4. It wasn't that long after production of the F3 stopped, then the spares situation with the electronics started to dry up. Electronics are and always will be the Achilles heel for cameras, but the F2 will function perfectly well because the only electronics are in the meter. However even the metering electronics are being remanufactured thanks to Mr Sover Wong. I cannot think of any other camera where this has happened, such is the following of the F2.
Over the other manufacturers, Professional cameras that were given a hammering by the press etc, non have stood the test of time as well as the F2. Forget about the Canon F1, F1n, all of the Canon Eos models, compared against the F2 they are simply toast.
(Oooops! I think I may upset some folks with the last sentence, but it is true!)