All episodes (https://en.wikipedia.org/wiki/List_of_Absolutely_Fabulous_episodes), specials (https://tvtropes.org/pmwiki/pmwiki.php/Series/AbsolutelyFabulous), and even the film (https://en.wikipedia.org/wiki/Absolutely_Fabulous:_The_Movie) are included in the polling.

Kind of hard to just pick one-
A few come to mind are "Poor", as well as the episode where Saffy re enacts her life on stage, and of course the last episode in the original series where Edina and Patsy are under the care of Saffy.

“Poor” and “Hospital”!