For Taskmaster UK: From the more recent series(!) Series 19 was pretty well regarded I think. Overall series 5, 7 and 14 (I think) tend to often crop up in the comments as fan faves. Haven't watched all of the NZ and AU ones yet, but I think the most recent NZ one and the AU one before this one were both very good. Overall it really doesn't matter much though because the shows are pretty much consistently good imo