I've found the Hermes j-flex have worked quite nicely for me so far. They seem to wear well and are a bit more open grained than the standards. I've also had a couple bad trims and joint failures on the standard Hermes in the last weeks, so I may be steering clear for a bit until it gets sorted.
It seems to me that the jflex get pretty good qc too, I haven't seen one go bad or come bad yet.
It's hard to spend big money on the finer grits since they go so fast. I don't mind the money for a 50 grit blaze because they seem to just keep cutting.