Best Buy for sure. When you can buy a game in-store and trade it back to them for tons more same day, it beats anyone hands down i.e. Warhammer $9.99 traded in for $25.60 the same week.
Sure, the TIVs dropped very recently and bannings came down but up to that point, no one came close to what BB offered in that time. Any new release could be traded for $40+