RuPaul's Drag Race *SPOILERS*

Dida can’t return because she’s going to be a guest judge on Drag Race France.

The production buffoonery that will force Coco to eliminate Kahanna or vice versa.

And to echo everyone else, Dida, MKD, Darienne, Pangina for AS9 (and get rid of the lipstick eliminations because they're tired and Asia might come back).
Villains would actually thrive in the All Winners format with the blocking. Villains always get eliminated in the traditional All Stars format because they tend to quickly chop any queen who dares to try to eliminate the strongest competition.