I'm not gonna lie, I came out with some terrific deals from both places and now have a backlog of the big games of 2011, but also had problems with ordering with both.
At Best Buy, I ordered the Dawson's Creek Complete DVD Set to send to my brother stationed overseas and after I got the e-mail stating it was ready to be picked up in store, I waited in line to pick it up, waited even longer for the associate to find it, and then was told that the stock shown online was inaccurate and they didn't have it even though I received an e-mail stating they had someone pull it for me. And then they couldn't cancel my order and I had to do it on the phone. I found the box set in the same store, took it back to the customer service desk and finished the transaction no problem.
Gamestop charged me $54.99 for MW3 while it was on sale for $44.99 when I ordered it online. I had to e-mail them, wait a week, and recieved an e-mail stating they would refund my CC. I recieved another e-mail a week later stating they had shipped me a package. It was a $10 GC to Gamestop. They never refunded my CC but sent me a GC instead. I probably could have called and bitched and been refunded on my CC too I but was done with it.
Best Buy were completely clueless and then lied to cover themselves. Gamestop made a mistake and then "fixed" it by forcing me to spend money there again. I vote Gamestop!