Personally, I find that it really depends on your local stores. When I worked at O'Reillys, I had a lot of idiotic coworkers who had no idea what they were doing. I've had coworkers tell people to compress coil springs using ratchet straps (which leaves us liable).
However, I had a different mentality than they did. I always strived to earn my customer's business and it paid off. I'd have customers that would wait a half hour or longer to talk to me when none of my coworkers were busy. I was on a first name basis with many customers, including going to lunch with a few of them before I moved. I'd go out of my way to help customers, including installing $1 PCV valves (as long as we weren't busy). No one I worked with understood why I would do that for people, however, when that customer came back and needed 2 Red Optimas for their diesel pickup, they would wait for me and give me their $300-400 sale.
It all comes down to the employees. To be honest, the parts are the same or very similar most of the time between all the aftermarket parts stores (Advance, Napa, O'Reillys, Etc). If you find a store that you like, with employees that you like then keep going there. However, I think that saying all stores of one brand are bad is a bit overzealous.
