I own both a KRG Bravo and a JAE-700, no experience with the Cadex though.
They are both in different classes, but both the top of their respective classes, IMO.
The KRG is an awesome budget chassis', and punches way above it's weight class. The ergonomics are great, and there's a lot of support from KRG in the way of accessories. You can really dress this chassis up if need be. It's a light chassis, and will get a bit front heavy if you stick a long and heavy barrel in it. My wife's KRG Bravo with 24" heavy Palma barrel was fairly front heavy, but changing the stock LOP spacers to two of the metal LOP spacers have balanced it out quite nicely.
The JAE is by far my favorite chassis, and I've been behind and shot most chassis. It's amazingly comfortable - you'll hear a lot of people say it's the most comfy chassis they've ever had. Build quality is very apparent, and unrivaled. The design and the features of the chassis is very well thought out, such as the mag well adjustments, rail and QD placement, etc. JAE when they were in business had some great and we'll thought out accessories for it as well, from the bag riders, NV bridges, the RRS/ARCA rail, which IMO was very well thought out and designed, much better then the flimsy ARCA rails you see attached to chassis' and stocks these days.
If you have the money, I would pick up a used JAE-700 on the PX here, they do come up for sale from time to time, and the prices are pretty good. If you want to save some money, the KRG Bravo is an excellent value proposition.