All of them are excellent for just plain hot anal scenes. I like Belladonna's work a whole bunch because she seems to get so much enjoyment from being the giving partner when it comes to rimming–it transforms this already sexual thing into something almost hypersexualized.

Crash pad, I forget what episode it is, it's the one with Jiz Lee and Syd–jesus christ is there some amazing rim work in that. It might be the most stark of the ones I've seen, there's nothing staged about it in the slightest and as a result it's hotter than hell.

Rock and Roll in my Butthole is a pretty decent movie, if you have a thing for that "alt" look it's a must-have. Plus, not a single scene goes by without anal of some form ( obviously )

Two that I think deserve to be on that list?

Belladonna's Cock Pigs. Specifically the scene with her and trinity Post, which starts off with an amazingly steamy bit of combo foot/assplay. And I'm not even a foot fetishist. It doesnt hurt that Post has a sort of "Librarian who takes of her glasses and lets her hair down and all of the sudden becomes hot" vibe to her, a particular weakness of mine. The anal work is top notch, as one kind of expects from Belladonna in this day and age.

Bitchcraft has an amazing scene with Annette Schwarz, Jandi Lin, Adrianna Nicole and Sindee Jennings. Basically Annette and Adrianna are two latex dommes who violate Jandi and Sindee for the better part of an hour. Features plenty of anal play, and it's seriously one of the hotter scenes in the series. tho other ones seem to lapse into self-parody ( dommes overacting their roles, mostly ), but this one seems reserved and a little more real. At one Point Annette pulls her rubber skirt over Jandi's head, giving her no room to move and basically forcing her to lick her–that seems like a legit move.

Honorable mention goes to the classic website Ideepthroat, which shows a very realistic pace and preperation for anal sex.