How about another take on this question: NEITHER!!
I prefer dealing with CarQuest 
Around here, none of the napa's are worth a @#$t, they cannot get the right part until they have made 4 trips to the shop, and by then the boss has crawled way up my behind because the car is still on the rack... As far as autozone, I worked there for a while and I tend to agree with whoever said armor all and such was all that they are good for, you wouldn't believe the returns, esp. on electrical stuff... Car Quest is the only one that will pull the book if the computer screen doesn't list or lists and don't make sense.. you wouldn't believe (neither do most of the countermen in my town) how much is still printed in BOOKS 
(They still make them things 
) They surprise themselves how much that they actually DO stock or can at least get every time I make them get out their old door stops and look stuff up the old way! As for oil and such, Wal Mart blows everyone else out of the water on price there.