I've only attended three ppv events, one Wrestlemania (Wrestlemania VIII), one Summerslam (2008), and one In Your House event (In Your House: Buried Alive), all in my hometown of Indianapolis, IN.
Between 1991 and 1996, I attended I think every house show/ppv event that the WWF held in Indianapolis. The streak was broken when Raw came to Indy in early 1998 (that was when Foley and Funk were pushed off the Titantron in a dumpster), and other than a Nitro show that I attended in 1998, I didn't attend another wrestling event in Indy until 2003 when Smackdown came to Indy (that was when the buildup to the Hogan/Rock rematch at No Way Out began).
I've been to numerous Raw and Smackdown shows in Indy since then (although I've missed a few in recent years). With the exception of Eddie Guerrero's final match against Mr. Kennedy, which was on a Smackdown taping held in Indy about 5-6 days before he died, none of the matches on Raw or Smackdown really stick out to me off the top of my head.
So needless to say the ppv matches are the ones that stick out. And thus I would say the best match I saw live is between three matches... Bret Hart/Roddy Piper from Wrestlemania VIII, Macho Man/Ric Flair from Wrestlemania VIII, and the Undertaker/Edge Hell in a Cell match from Summerslam 2008.
I would probably have to say that the two Wrestlemania matches were probably better matches (I would certainly put Flair/Savage over the Hell in a Cell, but I could definitely be swayed if someone wanted to convince me that the Hell in a Cell was better than Hart/Piper). I was so excited to be at a Wrestlemania. I had only been watching wrestling for about a year up to that point, and Wrestlemania VIII was only my 2nd live event that I attended, so it was very memorable. The Savage/Flair storyline was epic, and the matchup was epic to say the least. I wanted Savage to win so badly, and I was extremely excited when he did.
Piper/Hart was a great matchup that hooked me. Both Hart and Piper were two of my favorites, but I was still rooting for Bret. Piper's heelish tactics instantly had me worried that Piper was becoming a bad guy and was going to cheat to win. I was pleading with Piper to put the bell down when he came close to hitting Bret with it. And I was relieved when he put the bell down. That moment was so dramatic and is one of the two highlight spots in the matchup. The other one is the finale when Bret countered Piper's sleeperhold and pinned him, which I thought was simply one of the coolest things I had ever seen (still one of the best finishing spots in any matchup I've seen, another one of the many reasons that Bret Hart reeks of awesomeness to quote Edge and Christian).
Both of those matches are probably two of my favorite wrestling matches ever, and seeing them live makes them even more memorable to me. Those are probably the two best matches I've seen live.
However, I have to say getting the opportunity to see a Hell in a Cell match live is something that I'm very thankful for. There's nothing quite like the Hell in a Cell match, and it's truly a special thing to see live. Especially one as crazy as the Taker/Edge matchup was. The ending for that match has gotta be one of the coolest things I've ever seen live (not just in wrestling, but concerts and other live performances as well). It was brutal, it was exciting, it was fun to watch. My jaw dropped repeatedly throughout the match. I'm thankful that I can tell people that "I've seen a Hell in a Cell matchup live." That's certainly something that not every wrestling fan can say for themselves.
So yeah, I'd have to say it's between those three matchups. Some runners up would be the Undertaker/Mankind Buried Alive matchup (that's another rare matchup that only a few wrestling fans can say they've seen live, with me being one of them), and Batista/Cena from Summerslam 2008, and I got to see if I remember right, at a house show right before Summerslam 94 (which was when Diesel and Shawn Michaels won the Tag Team titles from the Headshrinkers), a tag team matchup between Bret Hart and Razor Ramon against Owen Hart and Jim Neidhart. After that matchup, Bret and Razor walked around the ringside area to greet the fans, and I got to high five Bret Hart which is definitely one of the biggest thrills of my wrestling life haha.
Great topic.