I watch Mighty Car Mods as well, on tv, together with my gf who also enjoys their show a lot, so that's an added bonus. I watch some stuff of Chris Harris, Petrolicious, EVO and DRIVE, but not everything. DRIVE Big Muscle is quite inspiring modification wise, lots of original stuff on the cars they feature.
The best YT-channel has to be
http://www.youtube.com/user/autoblogger - that most of the videos are made by me is pure coincidence!