From the best of my knowledge, there are no naff 90mm lenses. Essentially anything from the big 4 (Fuji, Schneider, Nikon, Rodenstock) will give you good, sharp results, it really just becomes a question of coatings, coverage and weight. That's not to say other brands will be poor, it's more to say that the big names may be largely taken for granted in terms of resulting images.
Brightness wise, F/8 is bright enough for most purposes and times of day, but I will say that as light starts to fall in the evenings, I start to struggle a tiny bit with my 90mm F/8. That being said, it is likely that it's to do with the fact that my Fresnel is likely not very well designed for wide focal lengths. Standard GG should be better I believe. My other 90mm, which is a F/4.5 is noticeably better, but I'm just being idealistic.
After the directly quantifiable (weight, size, brightness, coverage... and perhaps sharpness at a stretch), everything becomes subjective anyway. The beauty is that anything you buy is likely to hold it's value on the second hand market, so perhaps buy one or two (if possible) and do some tests over time. I can vouch for my Nikkor's, but the others in the big 4 will no doubt give comparable images.
The only other thing I can think of is that there is probably an argument for getting a lens in a newer shutter for higher likelihood of longevity... Maybe?
Edit: Apologies, I wrote my reply without refreshing the forum, so loads of replies appeared before mine when I hit post
