From what I tried, Stoptech discs crack all the time, and the pads that they give are junk out of the box. The calipers are fine, no worries there.
Brembos are awesome but you have to get the monobloc setup which are big big big bucks.
Grex kits are Brembos
Endless are perfect, they should be the standard to be compared as they are unreal. But they have an issue, they have too much of a stopping power, and you will be locking the tyres before you get used to them (thank god for the abs)
Rotoras are very good, but I hate how the floating rotors make noises when they warm up. You think they will explode for real.
Other kits like Kad, Hispec,D2 etc. I will not even discuss, they are very low budget, good for what they are, but not for a high speed vehicle.
And now we come to my choice of the JBTs. Well I was afraid in the beginning before I got the kits. Stopping power is incredible, repeatability excellent especially on high speed chases, looks they look as any big brake kit (everybody likes it), quality of calipers and flex of them I don't know. But for sure they are not Brembos monobloc, but i cannot see any issues with them.
Please take into consideration that the car is a street car and not a time attack car. So I cannot judge for this kind of scenarios. If I was going to build a time attack ride then brembos with ONLY slotted rotors would be the choice.
On the rears of the JBT i had to file the bracket about 2mm on the corner on the bottom of each side because it was a clearance issue with the ball joint if my memory serves me well. And I used the spacers of 1/4 mm that they had for the caliper mounting, in order to clear the rotor from the caliper. BUt of course the brackets of the calipers are big like they are going to hold a ship while breaking. The fronts got in as they were out of the box.
No noise from the brakes at all, and no issues with braking when cold or hot.
I hope I helped a bit.
Cheers
Dimitri