In my limited experience, a good line on one rod, may not be a good line on another rod. It can be expensive to buy and sell, but you gotta find what the rod likes.
Or google your rod, alot of manufactures will have a recommended line for their rod. While not always the best line for it, I find it's a great start.
But really, for nymphing, I doubt it matters, almost any of the big name line makers make a WFF that can throw a nymph rig 40ft.
T&T recommends SA Amplitude Trout for the Avantt for instance and they do not recommend over-lining. I went against that and bought some RIO nymph line...casts like crap. Picked up some SA and bam, casts like a dream.
For Royal Wulff...their Triangle taper is badass for bonefish/redfish flies...but again, its probably more rod specific, It was fantastic on a CORE 1 piece fast action, it was a little less impressive on a Allen rod I had, I did over-line both of those...which helped. I think its incorrect to just says dont buy this company their line sucks...its all application dependent.
Ymmv.