I have used the 4 Seasons R-4 compressors. I prefer the 'new' over the remans (specifically the units built for 134). They are another $30 or so (wholesale), and I feel better about their new units. Their parent company bought a lot of the tooling from GM when the economy went south. They also bought a lot of their competition (such as Murray, et al). I can't speak about Pep Boys, as I have only used them once for a tire while on a trip. I have used Delcos before GM sold the name. They failed just like everyone else (poor install/care = early failures).

I buy the 4 Seasons/Murray R4s because they work, and fit like OE. The fact that their parent company has a warehouse west of Chicago (Hinsdale/Willow Springs area) means I can get them (and other heater/cooler stuff) same day for a fair price. Do they fail - yes, but no more so than the original OE GM R4. I have had pretty good reliability in my customers' cars, and my own. I think if you get five years out of one, you have done OK. The big trick for longevity is proper installation & maintenance. Don't let them run out of oil.