Easily Back to the Future. Back then, the Delorean looked bad ***. Little did we know, it probably couldn't do a burnout OR go 88 miles per hour. :hihi:
It's not a teen movie in that it's not a John Hughes-style movie, but I think it's a teen movie when you look at the overall arcs of Marty and George McFly. I'd say Back to the Future is my favorite teen movie of the era.
OVERALL favorite movie of the 80's, though: Robocop.