I don't know if I can narrow it to 3 but I'll try
Hagler/Hearns is the fight that turned me into a full fledged boxing junkie when I was like 15.
Gatti/Ward 1 is amazing to me everytime I've seen it. Completely unbelievable fight and the 9th round might literally be the best round ever. Better than Corrales/Castillo 1 and Holt/Torres 2 to me.
My third pick, and what I actually believe to be the single best fight I've ever seen is Vasquez/Marquez III. I got to see the first fight ringside which was a great fight but I was disappointed with how it ended. The 2nd fight was incredible and one of my favorites but the 3rd fight was special. High pitched drama and I don't think that anyone expected to see it eclipse the first 2 fights that were both a winner and a candidate for fight of the year. The world had seen the controversial ending to Taylor/Chavez I and to see this fight come down to the last seconds of seeing Marquez knocked down to lose by one point was crazy. Not necessarily my favorite fight but it's the best that I can remember.
A few others that are high on my list...
Margarito/Cotto. Our house was buzzing with anxiety for this fight. One of the best fights I've ever seen and the best atmosphere I've ever seen for watching a fight at home. And Margs took the undefeated Cotto down for a win for Mexico.
Marquez/Pacquiao II. Another fight that we were buzzing for and I almost got fired because I left work early for this fight. I got there in the 2nd round and it was actually worth it. Incredible fight and maybe the closest we'll see Pacquiao to losing again. Also crazy that a knockdown caused Marquez to lose by one point, just the same as his brother a few months later.
Ward/Augustus. 2 warriors, straight up. Incredible action all the way through and a great action ending.
Morales/Pacquiao 1. Great fight and the 12 round where morales went southpaw to put on a show. It may have cost him the 2nd fight to do so, but they really gave fans their money's worth
