gamestop for sure, I hate those guys they are rip-offs. They dont offer any real incentive to buy from them and they practically offer you beans for your trade ins. I've completely stopped doing business with them.
I enjoyed ME2 but it didnt have as much to do as ME1, for that reason I voted for Fallout NV. Even though it had a lot of bugs it offered close to a hundred of hours of gameplay compared to ME2's 40 hours per playthrough.