I haven't read every single JY novel... but of the ones I have, DY is pretty up there as far as worst protagonist.
His WWY stalking, his illogical thought processes, the kotowing 1000 times to a statue... then saying he will practice BMSG and LBWB only because the statue instructed him to do so-- wtf? His lack of value in his own life even though he is the most likely sucessor to the great nation of Dali. Everything about him was terrible.
Again, I almost stopped reading DGSD becaue of DY.
*edit-- DY is not really the worst as much as the most annoying!