Hands down, I've never heard anyone do ads better than Cum Town[0] (seriously). Sometimes the reads end up being upwards of 15 min & in the middle of the show but nobody skips them. In fact in live shows the crowd will cheer when an ad read starts.
The trick is they have extremely tolerant advertisers who don't mind being basically slandered every ad read, having the promo codes and discounts read wrong, having the "don't read this part out loud" parts read on accident, etc.
Close 2nd is Hollywood Handbook, who also shits on advertisers and leads to their ad reads being the most listened to clips of the show. For example when Cards Against Humanity told them to say whatever they want [1].