Again, it's mostly WWE I've seen so I'd have to go for Orton/Foley at Backlash 2004. I believe it's the only time the fabled Bed O' Barbed Wire has made an appearance in WWE. Seeing Orton land back-first on the tacks was also pretty awesome (though probably not for him).
Agreed about the "I Quit" Match. It was only supposed to be 2 or 3 chair shots, and The Rock landed 10 if I remember correctly. Still one of my favourite matches though.

And if you're talking about sheer amounts of blood, the way Vince McMahon was bleeding during the Buried Alive Match with Undertaker suggested he may have bladed just a wee bit much.

I've yet to watch the whole Sabu/Terry Funk Barbed Wire Match from ECW, only seen little bits on Youtube....