, I think all the major brands have thermostatic valves now, but those two companies have been at it the longest. Personally, I've used a number of Hansgrohe valves (both in the higher-end lines and in the more consumer-oriented, lower cost, lines). Some don't have two separate knobs (one for temperature and one for volume) per se, but rather have a single control with different motions for temperature than for volume, but even those will let you set the temperature once and just use the volume-controlling motion forevermore without messing up your temperature setting. All the Hansgrohe products I've used have worked very well.
In the higher-end systems, the plumbing is a little different than traditional hookups, or at least you think of it differently. The hot and cold supply pipes go to the thermostatic mixer valve, which outputs the mixed water full-blast. You run pipes for that full-blast mixture to a number of volume control valves, one for each feature. That lets you control the flow through each feature separately (like a shower head, a rain head in the ceiling, body sprays in the walls, a hand-held spray, or whatever).
The traditional way has the hot and cold going to a combination control (both volume and temperature) and a "diverter" that sends the water either to the tub or to the shower. You can't control the flow volume separately, you just "divert" (route) the flow to whatever output you want on.