You're gonna like this one...
Nobody. There are companies that make one close enough that it works, but no one makes a decent, fully-tunable
VB that will work 100% of the time.
One thing to consider is that you'll need to select parts from the same vendor before they'll honor warranties. (Then it's still a shot in the dark if they'll actually warranty it, but that's another subject). My point is that an automatic should be bought as a package so the expected outcome is reached. Consider this: if you're converter is slipping, is it the converter companies fault that the valve body didn't send it enough pressure? The
VB company will blame the converter company and vice-versa.
Where are you located? You're best bet is to ride around in several brands of built trannys to figure out what's best for you.