glad I'm not the only MSTie here!
my favorite episode is either Laserblast or Manos: The Hands of Fate. Probably Laserblast because Manos was just unbearable to watch, even with the crew riffing on it. Gotta love Torgo, though.
Personally, I like their riffs on old 50s social guidance/industrial films more than I like their riffs on crappy movies. Especially A Case of Spring Fever. That one was classic.