Which Regional French accent is the most detested?

"Kuiper's 76 informants were given a map of France and asked to “circle and identify in writing any regions "where people have a particular way of speaking" (Kuiper 1999: 244). A composite map produced from these responses shows that Alsace—Lorraine was the second most frequently designated area (55/76 or 72% of responses); in this it was preceded only by Provence (63/76), and followed by the Nord/Lille (44/76). The informants were then given a list of 24 regional varieties of French, and asked to rate them according to degree of difference from the norm (that is, the respondents’ own variety), correctness and pleasantness. Lorraine French rated very highly (or badly) on all three rankings: 20th out of 24 for degree of difference (where 24th was maximally different, i.e. perceived to be furthest from the norm), 21st for correctness and 22nd for pleasantness. For these Parisians therefore, Lorraine French sits very near the bottom of the perceptual heap, as they believe it to be strongly divergent from the norm, incorrect and unpleasant. But what the Rennes test results show is that when a different method is adopted, namely when listener-judges are presented with authentic samples of Lorraine French (albeit urban, Romance-substrate Lorraine French), they perceive very little regional divergence, and are largely unable to link it to a particular geographical area when they do."

--- Perception and production in French dialect levelling / Armstrong & Boughton in Sociolinguistic variation in contemporary French