Only because you said "pass rusher:" Jared Allen. I think Ware is a better all-around football player, though. They're both in my top-five defenders in the league. And just for shits and giggles, in no particular order... Revis Pat Willis Ware Allen Umm... Kevin Williams? Nnamdi? Maybe Ngata? I would have said Polamalu or Reed a year or two ago, but you can't defend from the sideline.
They've both had three great seasons in a row. Allen is the more consistent of the two, so I chose him. Ware is definitely more versatile though.
I went with Allen for the pure pass rush. But I tend to agree with everyone else that Ware is the better all around end.
Not to burden this subjective conversation with statistics, but I thought this one might be relevant: Number of Quarterbacks Sent Running Out of the Back of the Endzone in Pure Fear: Allen 1, Ware 0
I would have said Ware as well, because of the great run stuffers Allen has at Minnesota, but I don't know anything about his time in KC.