Another mention of Blues Brothers ......absolute classic..NB I have seen Gladiator a lot ,mainly because my wife was totally obsessive about it and saw it at the cinema at least 14 times ..then the DVD of course , good one though
I answered Star Wars or Escape to Victory early in this thread, but in hindsight, my correct answer (and almost certainly that of anyone with kids) is probably Finding Nemo, or Toy Story or Cars, etc.
On TV only, I guess it would be a Frankie Howerd "comedy" made in the early 1950's, for some reason the BBC would always put this on at Xmas at a time when they couldn't afford a lot of the more recent stuff.
I believe the big UK film producers like Rank refused to sell films for showing on TV for many years knowing that they would lose any chance of re-runs in cinemas, hence the poor TV choice back then.
Way too many to think about and I would have diff categories rather than one film.
In no particular order:
Downfall
Indiana Jones
Ghostbusters
Top Gun
Ferris Bueller's Day Off
The Breakfast Club
Jurassic Park
Blade
The Day After Tomorrow (Yes yes I know)
The Last Samurai
Batman Begins
The Great Race