Having the choice, I would choose the customer service people who were happy and chatty and I would avoid the stores where they have a second agenda to sell you extra's or something you don't need in a bid to reach their targets.
I went into retail because I enjoyed the atmosphere of explaining the benefits of their choice and letting the customer decide, not to try and railroad them into 5 year warranties and the such like. And yes, people do get warnings for not selling enough addons in a month because its extra money for nothing to the store.
There are still good sales people out there who will sell you something for the right reasons. They are the people I would go back to. I think most of us would walk away from the pushy jobsworths though