Personally I’d go with Independence Day if I had to pick a movie that felt the most 90s.
Interesting that Point Break (1991) and The Matrix (1999) book ended the decade. Point Break focuses on white 20 something kids that dropped out and started surfing, the The Matrix focuses on a 30ish white guy going through an existential crisis. At the beginning of the 90s there was still some hope, that a person could find a small counter-culture and create if not a wealthy life, of something satisfying. By 1999 all hope was gone.