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).
That deffinitely wasn't that violent...
I agree with the end of "Mankind vs. The Rock" I Quit Match and "Mankind vs. Undertaker" Hell In A Cell... especially the latter.
ECW had some sick stuff with the barbed wire... but the most violent matches I saw were from the "King Of The Death Match Tournament"... got it from HMV on DVD.
Pretty much everything... It got so violent, that I thought Foley or Funk was going to get limbs cut off with a Sword.
I reccomend Hammy ect... Buy it just to see were Foley got his nickname from.