You put Zardoz in there but missed Silent Running?
Zardoz is terrible. Watched it a few months back and aside from some neat ideas and imagery its actually one of the worst films I have ever seen. A film so bad it actually hurts.
It's essentially takes what would make a good Doctor Who or Blakes 7 story and turns it into the longest 100 or so minutes of your life.
I wanted to like it, there of bits of it that I think are really quite good, but it's just a confused po-faced mess that gets worse as the movie progresses.
That said, you can pick Zardoz up for pennies on Amazon so if you are interested in such things (as I am) at least you don't have to pay through the nose to get a copy. Think mine literally cost me a few pence + the postage!