Having a brother and cousin who went the UTI route I have quite a bit of knowledge on the subject. Brother works at Mini/BMW and cousin works for Lexus. Both are making much more than I ever expected ($75k-100k in Socal).
First off, to clear the air... most are going to say these programs are a waste of money/time and that can be true. My brother has told me of countless people who dropped out or didn't take the program seriously, and for them it was a waste of money/time. From what I understand it makes no difference which program you go through UTI or Wyotech, not sure about JC's, but as long as you take the program seriously and do well, you'll actually have options available upon completion.
To clarify, both my brother and cousin graduated near the top of their class (most certifications, badges for different programs, and so on). Within the programs you can specialize in certain automakers and this key to getting in with the dealerships after graduating. Before my brother graduated he seeked out BMW dealerships to make sure he had job lined up. After graduating BMW flew him out to their training program for a couple months and once back he was one of the mechanics.
I can't speak for all the dealerships, but it seems like the pay is decent (usually starting around $20/h) and then several ways in which you can boost that amount by expanding your knowledge. To point out, $20/h might not be great, but I think most dealerships go by the amount of hours you flag rather than work. So if a job pays 10 hours and you complete it in 8 hours... you can see how the year end earnings can be much better than initial thought.
Anyways, if you have any questions feel free to ask. Also, don't be discouraged by people shitting all over these programs, they can work out if you take them seriously (just like most things in life, if you ask me).