depends on the part... if i'm just getting oil or something simple, its usually advance... but if its for one of the custom parts, like drive shafts its either NAPA or carquest because the people at my local branches actually know how to read a micrometer and know the difference between a spicer 1310 and a 1350 and what those numbers actually mean... lol
when it comes to performance stuff, its usually either poly performance or 4wd...
There' an Autozone close to my house. If it's just motor oil or some basic component I usually go there. There's an O'Reilly's about a mile further down the road. I usually go there for rotors and things.
The local carquest, they warranty parts and labor for a year if they install them, and a one year warranty on all parts. It depends on the local napa, one is better than the other. I only use schmucks or advanced if it is a sale/emergency/late at night.