I have a lot of trouble ranking his movies. Mainly I think of Pulp Fiction and Inglorious Basterds as my top two but there is so much mobility between the other spots.
Like, for instance, I rank Django, Jackie Brown, Hateful Eight, and Reservoir Dogs so close to each other that any one of them could occupy a 3-6 spot and I wouldn't feel badly about it because I think they're all awesome. Jackie Brown probably takes the award for his most underrated. That is just an awesome movie top to bottom and, interestingly, it's probably the least Taratino-ish while still having a bunch of his sensibilities.
I think Kill Bill movies are fun but never been a huge fan. Death Proof I'd rank as his lowest. It's not without its merits (mainly anything involving Russell), but the first part with Poitier, Ferlito, Ladd, and the initial really creepy scene with Rose McGowan is so much better than the latter half stuff with the second group of girls that it feels really uneven. Also, as much as I laugh hysterically at Stuntman Mike's Looney Tunes-esque scream after he gets out of his car in pain and injured, the axe kick destruction of him seems waaay out there lol. Even for Quentin.
Death Proof also works so much better within the context of Grindhouse. Grindhouse as a theatrical experience was friggin awesome. One of my favorites from the past decade plus. The two movies, the fake trailers, just the whole vibe was great. But separate Death Proof from the (in my opinion) superior Planet Terror and the fake trailers, and it's nowhere near as good.