As I remember it the above version is a fairly literal adaptation, the Tarkovsky one is more poetic... dreamlike... arguably boring, and the third version sort of delves more into "If they don't know they're not real how do we know we are real?" stuff but in a hamfisted Soderburgy way.I've seen that one, but not the Clooney remake. Do you think the clone aspect would've been better with more of a subtlety? Its been a while since I watched Stalker, but I remember the subtlety working in the films favor, culminating to the very last scene with... what was it, a glass of water?
edit: haven't read either of the books though, so perhaps the subtlety factors in that way.