Mine would be Clemson 2020 at Notre Dame stadium. Thrilling overtime win against the #1 ranked team with only ~15k others in the stadium due to Covid restrictions. I’ll never forget it!
I haven't been to many football games in my time. Maybe I can count them on two hands and that includes situations where I was part of some promotional event.
But in undergrad, I got to watch Steph Curry play a lot from the student section and it was a delight. We knew he was special way back then, he played with a chip on his shoulder and we thought maybe he would do okay in the NBA. I had no context because there were no other NBA caliber players in the entire conference, so we thought he was good and maybe good enough to make the NBA and stick around a while. But I never thought he would become the hall of famer, record setting player he is today.
Some additional context about Curry in college: he was great, we just didn't know how well the talent translated. Our conference would get maybe 2-3 games a season against top tier teams (UNC, Duke) and it would always be a blowout. The player of the year was a guy named Kyle "Sir" Hines at Greensboro who was a 6'6" (1.98m) center setting all sorts of historical records. And he even did well against those top caliber teams. And Curry was also setting records, but I think Kyle graduated first and then didn't even make an NBA roster and didn't do well in the Summer Leagues.
So we expected Steph Curry to end up somewhere in that range, maybe he would make a roster but probably not have a long career because he was smaller and didn't have great handles for a point guard. A lot of things broke open for Steph at the right time, from the NBA changing to an easier scoring softer rim and relaxing defensive rules, to teams money balling the sport and figuring out that 3 points at 40% was much easier than 2 points at 60%. And even then it was a difficult choice for Golden State to stick with Curry those first six seasons, over Monta Ellis. They gambled, and it didn't work until they changed coaches to the first time coach Steve Kerr, which tells how well Golden State was respected. And the rest is history.
Kyle Hines ended up in Europe and had a very good multi-decade career there.
Mine by far is July 7, 2021 when the Bolts won the Stanley Cup at home versus the Canadiens. They had won the previous year, but it was in the social distanced "bubble" finals in 2020, so this one actually had people at it, and they won.
I had painted my beard blue for the entire finals. The big fan group I'm with had been marching through the city down to the game every game night for a few weeks, and then to win it all... Just so so good.
2019 Virginia Tech vs UNC. Game went to 6(!) overtimes. Hokies won. I swear that game took a few years off my life. I brought my (then) 9 year old son and told him “I’m sorry, that is officially the most exciting game you’ll ever see. 9 years old and that’s as good as it will get.”
Not football, but I’ve attended some great baseball games. I watched the StL Cardinals beat the astros 12-11 when they had Puljos, saw a walk off in the bottom of the 10th once, and attended a cards royals game where the cards threw a no hitter.
Mine is Browns @ Broncos in 2018. It was Baker Mayfield's first year as a starter and the Browns were still in the playoff hunt in December for the first time in ages. The Browns also hadn't won in Denver in 30 years. There was a ton of excitement around the team and Browns fans took over the stadium. It came down to a sack on 4th down and when the Browns won the stadium went nuts. I'll never forget that one.