Not sure "who's the best" as like many parts there are several who do good work.
Moser, Dr-Diff are a couple that come to mind, others may help you on that.
Gears? What transmission are you running and do you do lots of highway driving? 3.55 or 3.73 are a nice gear, if you like good response 4.10 perhaps, but if you drive on the freeway heaps 4.10s won't be so good.
Lots of variables.........