I don't trust half the schmucks doing those $20 oil changes. I doubt they care enough, heck some of them have been caught not even bothering to change the filter.
If I do it, I know it is done right. Plus, for how much I drive and how I want my vehicle to last, I don't use cheapo oil.
I let the dealer change my oil while the warranty was in force as already mentioned, you have proof you maintained the service schedule. They overfilled it by a Qt. once, brought it back to them, when I did my first change the drain-bolt was on so tight I had to put the car on stands and use a breaker-bar to loosen it!. Oil filter was the same, I think they had Magilla Gorilla working in the lube dept!. My brother had a change done at Jiffy lube, next morning he saw a puddle of oil all over his driveway, the bolt was on by 2 or 3 threads, thank god he didn't start it with an empty oil pan..