It's staggering how little effort is made to source good prints on TV. Aliens: Special Edition was only ever finished as a video in the 90s though - I don't think a film print exists, so I guess it's a particularly tricky to source something.
By and large, people do take care with DVD though, so to be honest C4 should have gone down to HMV and bought a copy for a tenner and put that out instead...
As for the best sequel debate, think it's time for a new thread!