Quoted from CaptainNavidad:With apologies in advance to the OP who is looking for least favorite designers, I’d like to qualify his thread title and offer a name for most underrated: Mark Ritchie. He’s the creative genius behind the greatest pinball ever assembled – Williams Indiana Jones – and is responsible for a number of other gems such as Fish Tales, Diner, Taxi and Police Force. If memory serves, Pinball Magic is also largely his vision as well. To me, he is the greatest designer this hobby has ever known. Period.
His sample size is too small to call him the greatest, but his success rate was very high for the one's he did design or helped design.