What's the best rebuild kit for a 1999 4x4 transmission?

 

IMO I just use whatever is affordable. There are different brands of clutches but I don't know what the difference is between them. If this is for a stock factory 4.3 4L60e transmission it will not matter. There are BorgWarner(tan), Raybestos(blue) and Alto(red). The Borg Warner and Raybestos are about the same. Alto is pretty much race only because they they grip very well and therefor wear quickly.
As far as kits, they will all come with the factory parts and you'll have to buy parts separately if you want something different.