I'd like to see both Aliens and Alien 3. Alien:Resurrection i saw at least four times and saw Alien 3 in an illegal basement cinema showing bad quality vhs copy with typically monotone Russian voice over, but that added to the murkiness.
Saw Alien couple years ago when the Covenant came out, but the experience was surprisingly underwhelming, dunno why. Maybe seeing Prometheus took something away and the space jockey scene no longer was as effective.
Blade Runner on a huge screen in a packed cinema couple months ago was great though.