Okay, no particular order but here we go:
Jurassic Park (1993)
2001: A Space Odyssey
Indiana Jones (All four of them)
Galaxy Quest

Of course there are lots of other movies I’ve seen that I thought were absolutely fantastic but not things that I would return to often for casual enjoyment.
Metropolis
Mr. Smith goes to Washington
Twelve Angry Men

Then there are the films that I thought were pretty darn fun and/or entertaining but again, wouldn’t watch as much as those first ones.
Blade I and II
The Lord of the Rings Trilogy
John Carpenter’s The Thing
They Live