I have a Drewtronics probe and an older style Tormach Passive probe. The first probe I had was a WildHorse probe.The Tormach probe worked great for a long time, but Mach had a habit of not stopping when the probe activated and it crashed the Tormach probe quite a number of times as a result. I've rebuilt it many times. It is still usable and I keep it around as a backup. Tormach doesn't sell parts for this probe, once it's beyond repair that is it.
I think the important part of a touch probe really is the ease of adjustment and the stability of the adjustment, and of course repeatability. Both the Tormach and the Drewtronics took some getting used to in their adjustment. The WildHorse probe I found to be so unstable that I had to adjust it basically before every use. Once the other two were in good adjustment they stay pretty good assuming no crashes. I haven't tried one of the new Tormach touch probes, but since you can't even buy the one I have anymore, I won't go into detail on it's adjustment. For the Drewtronics unit, it used four set screws. It's a fairly straightforward process, but the set screws use a bit of a course thread, and getting that last lit bit can be a challenge. The last time I calibrated it I was able to get it down to less .00025" runout. It's remained very stable at that. I can probe and run Side B on a part and generally get a very close match with no witness marks. Luckily UCCNC solved my probe crashing issues, it always stops when it should. So I haven't had to rebuild the Drewtronics probe. It sounds like Drew sells parts though, good to know.
I have the non TTS Drewtronics, I simply didn't have TTS at the time of purchase. Now that I have TTS I kind of wish I had the TTS version, but I'm not inclined to let the probe rattle around on the tool carousel anyways. So the only thing the TTS setup gains is that it shortens the probe over the use of an ER20 TTS collet like I am doing now.
I have looked at other probes, the new Tormach passive probe looks good, as does this Kurkesu unit;
https://tormach.com/passive-probe-probe-only-50355.html
https://www.kurokesu.com/shop/TPA2
As it stands, the Drewtronics probe is very affordable and is working as well as the Tormach probe ever did, but it's also cheaper and apparently rebuildable. I'd say that kind of speaks for itself.
Also, if you get into doing a lot of probing check out the ProbeIt plugin for UCCNC. I purchased it a while back (I think it's ungodly cheap, like $20 or something). The plugin provides a probe calibration, a large number of setup operations for setting up work offsets as well as produce DXF outputs for probing parts. I can't seem to get my head around the built in UCCNC probing, the language in the manual is lost on me, but the ProbeIt plugin was intuitive right off the bat. I know others have had better luck with the built in probing though.