I can only speak for the TST. It works very well, and the problem of the monitor losing the sensor signal is ameliorated by the installation of the repeater. Which it now comes with, mine didn't and I've lost the signal a few times over the years. The actual loss isn't a big deal, but the fact that the TST doesn't notify you of the loss for up to hour is a big deal IMO.
In all honesty, I believe both systems work very well. And are good insurance. I don't see the color monitor as being a big selling point, in fact I really don't see the point. I rarely look at ours, instead I rely on the alarm to work. And it does.