NAPA store
I know of a lot of guys who stay loyal to NAPA for the "car guy feel" of it.
I will tell you that I know of a lot of shops in my area who won't go to NAPA as first call. The guys who own them absolutely will not honor warranties on any warranty part unless you spend so much money with them each month or if you're buddies. Once you stop warrantying parts for your commercial customers, you're pretty much done selling to commercial accounts.
A lot of commercial shops don't do business with them because of this. The stores here are still open because the heavy DIY'ers think it's a "professional" store where all the shops do business. It couldn't be further from the truth.
I'm not saying this to say all NAPA's are that way. When the NAPA here was under the previous ownership they would bend over backwards for customer service. The new owner? He's a good guy, but unless you're a buddy he won't deal with you. A lot of his shops pay retail price and only his poker buddies get a break, even though parts sales account for 50% of their business.
On the flip side of that we have a member here who works for NAPA in another area and is a good friend of mine. Most of the business he has is to commercial shops. His stores will go to bat for their commercial customers. It all comes down to ownership.