You could point to a few other possibilities. Alexander Gustafsson giving Jon Jones all he could handle in 2013. Randy Couture shocking Chuck Liddell in 2003. Lyoto Machida capturing the title from Shogun Rua in 2009.
But for my money, what happened Saturday in the main event of UFC 275 tops them all. When Jiri Prochazka choked out Glover Teixeira with 28 seconds remaining to win a bout he was losing on the scorecards, we all had not just a new light heavyweight champion, but the best title fight in 205-pound division history and a short-lister for the best title tilt in any weight class.