Ctein's tests in Post Exposure 2 tested El Nikkor 135mm, Rodagon 135mm, Rodagon 150mm, and Componon S 150mm. Conclusion: all 4 lenses had very similar contrast and resolution; the Componon S 150 mm had the best contrast of 4x5 lenses, but wasn't quite as sharp as the 135mm Rodagon. You can download a free copy of the book on his web site: http://ctein.com/booksmpl.htm

I suspect their is more variation sample-to-sample among the best lenses than there is brand-to-brand. Enlarging/process lenses have among the most stringent requirements, and I doubt of the major manufacturer's there isn't anything they don't all know.

For smaller formats, I have El Nikkors, that I am very happy with; I have a Comparon 150 mm that is very sharp, and I like--even though it's only 4 elements. Comparons are optimized for a 4x enlargement ration (Componon's are optimized for a higher enlargement) and this might play into it. I've also bought a 135mm El Nikkor, and a 150mm Rodagon (they were cheap), but haven't tested them yet. I got the 135 in case I want to make bigger enlargements than the 150 allows.

One thing to keep in mind is the mounting size: lensboards have become very expensive, so it might be worth it to get a lens that you can mount on your existing lensboard.

Charlie Strack