The question is favourite, so the 90s for me. You had a lot of good historical films about the 70s & 80s, pinnacle of action set pieces before CGI took over and a lot of legends with upcoming actors of the 00s.
Just a taste would be:
Heat, Casino, Demolition Man, Cliffhanger, Terminator 2, Gattaca, Misery, Shawshank, Truman Show, Seven, Silence of the Lambs, Point Break, Schindler's List, Pulp Fiction, Unforgiven, The Insider, Cable Guy, New Nightmare, Kingpin, Dumb & Dumber, Maverick
As for my decade picks, I'm a simple man:
30s: Gone with the Wind
40s: Casablanca
50s: Rear Window/Spartacus (most production took place in 59)
60s: Dr. Strangelove
70s: Rocky II
80s: Rocky IV
90s: Heat
00s: Gladiator
10s: Wolf of Wallstreet