I selected product quality... but in my opinion, the good selection, quality of product, etc are really tied to customer service. I am sure the OP was specifically talking about phone support, returns, etc. but having a solid selection of products, high quality, reasonable shipping rates and turn around really fall into Customer Service to me.
We have a new LHBS here and I have swapped to it because I can walk in - be treated well, and if they don't have something in stock, it goes right onto a list of new orders. I even get an email or text if it has arrived. Great folk, and they don't EXPECT me to pay a premium in their shop, and work hard to earn my loyalty.