I'm a huge Sci-fi fan & the old Sci-fi beats much of the new stuff.
The day the Earth stood still is amazing but the new version is rubbish, nowdays the special effect often dominate the whole film but in days gone by they couldn't rely on special effect so they had to concentrate on storytelling.
I adore the old Ray Harryhausen films, so what if the creatures didn't look fantastic, so what if you could see the occasional fingerprint left by the stop go animation techniques, they were amazing films.
Very few remakes live up to the originals, about the only Sci-fi remake that trumps the old version is War of the worlds but I read the novel several times a year & have always wanted to see the martians stomping around in tripods instead of hovering manta ray shaped war machines, I still love the old version as once again it's more about the story than the effects
One non sci-fi classic that I adore is The Birds, every time I watch the school attack the song the children are singing whilst the birds gather sends a chill up & down my spine, however, I always laugh at the two lovebirds in the car, when it corners & they lean with the car I can't help but chuckle.