first of all, vader is a dark lord...sidious was very strong, im not denying that, but i think he was strong in a smart way. vader lost to sidious, and if we are going by the movies, he did kill sidious (it was some stupid eu book that brought him back)...luke lost to the emperor because he threw down his lightsaber...he underestimated sidious's powers....vader lost to luke because he underestimated the effect the comment about leia would have and luke used a quick strike and the darkside to fuel an unpredictable attack...anakin lost to obiwan in ep. iii, which is not in the first three movies like you are talking about, same with dooku...anyway, the point is, vader is the best! :D
<{POST_SNAPBACK}>
Don't know buddy, seems pretty messed up there....