The only movie I've enjoyed (and watched 20+ times) is The Final Sacrifice
"Buy me ANYTHING in there with Larry Czonka on it. I'll pay for it." Classic. I haven't explored the Rifftrax yet, but worth mentioning here in case any MST3Kers aren't aware of it: The Film Crew is a short post MST3k project that is (mostly? still?) available on Netflix.
My fave MST3k features, in no particular order: Final Sacrifice, Squirm, Overdrawn at the Memory Bank (ft. Raul Julia!), Phantom Planet, and The Girl with the Golden Boots.
I watched Girl wi the Golden Boota on Netflix recently. So much fun rediscovery these. Side hackers! Wish NF had that one.