For me all of my favourite Horror franchises are Horror/Comedys. Obviously there not super funny, rather there a little bit lame, however i dont take horror films to seriously. By this i mean i dont get scared or freaked watching horror films, so adding a few one liners and taking away that super serious edge adds to the enjoyment for me. For example; taking chucky or leprechaun to serious wouldnt be as enjoyable.
BTW some of my favourite horror franchises (all of wich are horror/comedys in a way :) ) :
A nightmare on elm street.