Hmmm...
I know you asked for "the most exciting", but here's just about everything...
I haven't been to a lot of live sporting events, believe it or not.
I find it exciting watching the new single-A Phillies affiliate team, the Lakewood Blueclaws, in the next town over. Last year I went to the Single-A All-Star game. Minor league ball is a lot of fun, and now that we have a team nearby, I don't have to go to Trenton anymore. But, I will have to anyway since Trenton is now a Yankees affiliate

Speaking of Trenton Thunder, one year this one kid really impressed me, and I said to my friend how we were gonna see him in the big leagues very soon: the following season Shea Hillenbrand played for the BoSox and had a great year
The only boxing event I ever attended was last September, where a local venue (down the street!) featured an ESPN2 bout featuring former IBF super middleweight champ Charles Brewer vs Freeman Barr. There were also two bouts with Toms River natives. Boxing is nice on TV and all, but I never thought I'd enjoy a live fight. I can't imagine being ringside for a real fight!
MLB, every Yankees game is fun to watch live! I never go to playoff games, though - can't jinx it!Besides, I do like watching it on TV for the better view and analysis (and cheaper beer - lol). In retrospect, it was great seeing Pete Rose play in Philly when I was a kid. And who could forget Reg-gie!
NBA, I've only been to 2 games in my life - one with Plaw recently, and the other w/ a bunch a teens from work. The latter, needless to say, I couldn't pay much attention to the game as I was their counselor. Both were Nets games.
I'm so lazy when it comes to sports I guess. I've been to like 1 NFL game - Giants. I went with my dad, who was invited to attend w/ our (then) state senate president. Great seats, of course, and even a clubhouse lunch
I've never been to a hockey game, but would like to once just to see what it's like. Devils, of course
The most exciting event I never attended, but watched on television, was in 1998 when our hometown heroes won the
Little League World Series ! This town was buzzing for weeks/months after that - and the following year when they won the Eastern Division.
And besides all those great Yankee teams - watching the 1986 World Series was very exciting. The only time I ever rooted for the Mets (sorry, SC)
