Oh man, O'Reilys over here is absolutely awful. Unless I'm getting something generic like an oil pan, I try to stay far clear. The employees seem stoned and clueless, the other day I was looking for push mount zip ties and tried to show them, and they treated it like a mythical unicorn even though I had one with me. Another time I bought two belts for my alternator and they were different sizes.
I end up going to autozone frequently because it's right by my house and open after I get off work (during the summer at least). Napa consistently supplies top tier products with knoledgable employees. It's just a mile or two further from me and harder hours.