I don't really care about the extra speed from the Fuji since they're both enlarger lenses and will be used in printing, and I can't imagine why I'd have it wide open ever.
More so the quality differences between the two.
Since I can get ahold of the Nikkor with a Beseler board for $95 or the Fuji for $10 (And have to get the board separately, another $20)
Is there a major quality difference?
I've used the Nikkor so I know its on the level of what I want, just really curious as if there's something wrong about the Fuji.
What label does the Fuji lens have? If it's a Fujinon "EX" lens, it's the latest version of their lens, multi-coated, and damn good. I have a 90mm and a 50mm from this series for my enlarger, so I know the quality only to some extent.
If it's Fujinon EP or ES, it means older with probably mono-coating, but still pretty good. If it's a Fujinar lens, just avoid it.
Meanwhile, El Nikkor is what it is. If you like it, go for it. Or you might want to get both since the prices are pretty low.
In general, based on my own experience, to me Fuji lenses tends to produce less contrasty and less grainy than Nikkor lenses. The way I desscribe is that the images produced with the Fuji lenses are rather quiet-toned, on the other hand, the ones with the Nikkor lenses, a bit wilder-toned. But you can't really see the difference if you are enlarging small, like 8x10" and maybe some lenses don't have these characterisitcs at all.
But then you're getting a used enlarger lens, it also depends on the previous use of the lens.