I guess if you're talking about 'twist' endings i'd have to go with The Usual Suspects, first time watching.
but some of my all time fav endings are
The Good The Bad And The Ugly - Ecstasy of gold soundtrack with the Mexican stand off, epic, RIP tuco
The Long Kiss Goodnight - The long close up and Shand's face, you see every emotion possible before he realises his game is up, then it cuts to black
2001 a space odyssey - The illuminated colours, confusing timeline + space baby blew me away, what a visionary. a 1968 release...
Funny Games - evoked actual anger in me! loved it
Inception - I know people say movie is hyped and I've read numerous times that its 'over-rated' and so is Nolan etc. But I enjoyed it, and that ending
The Departed - rat fuck
a few that sprung to mind