I think Inglourious Basterds is my fav. Can watch that one on repeat and still be entertained. You can say it didn´t do anything new, but I feel it was just the perfect culmination of everything he does well. Dialogue, suspense, hilarity, cartoonish violence and great acting. The fact its a Second World War setting makes it an unapologetic pisstake as well.
Followed by the two Kill Bills and Pulp Fiction. Again watched them countless times. Some of the best films made when they first came along, and they haven´t lost anything with time.
Will have to watch Hateful Eight again, as the only time I´ve seen it was on a longhaul flight.