My favorite queen is an Olivarez Italian. Somehow she was accepted into a weak laying-worker hive, and quickly turned it around to being my biggest honey producer. Solid frames of brood, gentle bees, quiet on the combs, no signs of disease, overwintered fine. The only slight negative is that they use a lot of propolis. On a hot summer day it's like the queen excluder was dipped in laffy taffy. But I didn't really find that that made it harder to work the hive, so whatever, that's fine.
My only comparison points are the three queens that came with my original Hudson Valley Bee Supply nucs, a couple queens my hives raised for themselves, and one purchased from another supplier. The others had great customer service, and the queens performed OK, but just not as well.
With this small sample size, my experience is likely just random, but I really wish this sub-forum was more active, so I'm throwing in my experience anyway. Hopefully more people who've purchased 20+ queens from 5+ different producers will create posts here, as that would be much more informative. I'd especially like to see posts of the form, "I've tried X, Y, and Z. Now I purchase most of my queens / hive tools / frames / whatever from Z."