mm hate...
yuu watase's works... so cliche and they're all the same. the worst one would have to be fushigi yuugi.
in fact a large number of shoujo anime/manga are painful just because they are so lame and cliche and completely
unoriginal.
Another one of these would be kimi ga nozomu eien.. painfully boring.
DN angel was really bad. The manga was amazing and the anime was trash
yu gi oh - the art is extremely amateur looking
evangelion - started good then ended up trying to be cool, abstract and just became lame, try hard and boring (not to mention pretty frikkin messed up) not to mention shinji is such a twat.
love hina - this is completely over-rated, its complete fan service, the protagonist needs to grow some balls, its not funny at all and all the women are ..b_tchy can be the only word for it
theres probably more but these are the ones that come to mind