Of the Science Fiction Films of the 50s, these came out during my childhood (3 to 13 years old) and I can say I saw all of them and of these, Them, The Thing from Another World, The Day the Earth Stood Still, Forbidden Planet and War of the Worlds stand the test of time as being among the best Sci-Fi films every made even with their special effects being no where near the CGI standard of today. They had plots, something seldom found in Sci-Fi flicks current produced.
Plus, 1954's Creature from the Black Lagoon made a man of me in my seventh year as I fell completely, totally in love with Julia Adams... and am still of that affection 59 years later today.
And while Plan 9 from Outer Space is touted as the worse Sci-Fi film ever made, it caused 1994's Ed Wood to be filmed and that makes it aces with me as Johnny Depp nailed Ed Wood's character and Martin Landau's Bela Lugosi is superb.
I’ve only seen 41 of the 50. I’m ok with that.
I’m sure I could add to the list significantly if it weren’t 0730, but The Fifth Element should be on the list as well as Mars Attacks.