I've had failure with Omni 2K PPG rep paid for the re-do. Paint comming off in sheets, with powder primer residue on it. Car had not even left the shop yet. Hadda strip, and re-prime, with something else. I chose to use Slick Sand on the second go 'round, paint has held up now for about 10 years.
I used DP for many years, it was the "Cat Daddy". DPLF OTOH is crap.
I used Sikkens Autobase for years, was good stuff, prime formula would match perfect. They took out my system, and replaced it with Autobase Plus. I was sorely disapointed with it, and went to Global. While Global is good stuff, It's kinda expensive. And sometimes it's more cost effective to order a pint of DBC, than to mix 8oz of BC.
I've been using 2002 clear since it came out, and just love it. But I tried SPI universal a couple years ago, and found that I like it as well.
I'm still up in the air about SPI epoxy, While it seems to be good stuff, I've had a couple of issues crop up recently, and I cannot say definitevly what the cause is, untill I get into the repair. Both issues, are on my own vehicles, so it will be a while before I get to that.
I will say this though, steer clear of Nason if you want a quality job that will hold up for a long time.