Apocalypse Now - Theatrical. Brilliant. Redux is interesting in some ways but the pace is terrible and the plantation scene is super boring, the film has no impact.
Alien - Director's Cut, but only barely. Nothing wrong with the theatrical, I just like the added scenes and couple of nips in the DC, find it slightly stronger. Should have cut out the cocoon scene though but its not a deal breaker.
Aliens - The first version of this I saw was the "TV version" and it's still my favourite. It adds the scene where Ripley finds out about her daughter, all the scenes in the sentry guns sequences and the moment at the end where Ripley and Hicks exchange names. All the best footage from the SE, IMO. Otherwise, I find the SE too bloated and prefer the tighter theatrical (but I miss those three deleted sections).
Blade Runner - Final Cut. Every change improved the original and none of them detracted. Definitive version of the film.
Terminator 2 - Theatrical. I like the terminator-John Conner moments in the desert and an extension here and there but otherwise find the SE unnecessarily bloated. The original is stronger. Like Aliens an ideal version for me is in between the two but since there isn't one I watch the theatrical. I miss those desert scenes though.