Nothing in English football can ever top the ending of the 1999 UEFA Champions League final. The Aguero one was one of those all-time dramatic moments too, but anyone who puts that above the Solskjaer goal is either too young to remember 99 or probably a die-hard believer in the "OMG man yoo killed football man!" mantra that fans of almost every other English club have been bleating en masse for the past decade.
The game has changed so much in the 15 years since that epic season that the feat of that time can almost certainly never be repeated again. To win the Premier League, FA Cup and Champions League in one season is extremely unlikely now, even more so than it was then ... but to do it playing fast, attacking football, with the core of the squad made up of genuine top class home grown players from your own academy, and in such dramatic fashion? It'll never, ever, ever be topped. Barcelona 2011 is the closest thing I can think of but I didn't really enjoy their style of play as much.