It is really tough to answer your question when I don't know which kits you are actually looking at. I don't recall trying any of the kits in the following list (but I may have had a taste of the Cru Select a few years ago). My comments are based on my perceived brand quality.
High End Choices from their web-sites:
RJS En Primeur California Sauvignon Blanc - should be best one on this list
RJS Cru Seect New Zealand Sauvignon Blanc - should be second best
RJS Cellar Classic Sauvignon Blanc
CC California Reserve Sauvignon Blanc - no experience with this brand, but wouldn't expect it to be better than Cru Select
I had a few bottles of the Vineco KenRidge Showcase New Zealand Sauvignon Blanc, and really enjoyed it, but again a few years ago. Quality wise, it would be about the same quality as the Cru Select. KenRidge Showcase also has a French Sauvignon Blanc. There are also the Winexpert Selection kits to consider. Plus a variety of less expensive lower end kits from all the manufacturers.
Personally, I have been wanting to make a batch of the KenRidge Showcase New Zealand Sauvignon Blanc but haven't got around to it yet, as I made a lesser limited edition KenRidge Classic New Zealand Sauvignon Blanc in 2008, and still have some left.
Steve