Re: Fave Sci-Fi of the 70's/80's
The Terror of MechaGodzilla - the last of the original Godzilla films and one of the best, with a surprisingly horrific storyline (at this point, the series was being aimed at children) about a discredited scientist who willingly sells humanity out to conquering aliens and his daughter who becomes their tool (literally). Plus there's lots of Godzilla kicking the crap out of MechaGodzilla and his somewhat unmemorable dinosaur sidekick, that's nifty too.
Phase IV - a film I first encountered on the very early (non-cable) episodes of MST3K, this is actually a very interesting little film about normal-sized ants who acquire intelligence during some sort of odd cosmic event and begin to wage war against humanity, first fighting a pair of researchers sent to investigate the ants' actions.
The 70s are not my favorite decade for scifi films. Nor are the 80s. I have a lot more favorites from the 50s and 60s, if I were to list them I could go on for pages.