Sci-fi may be my favorite film genre.
There are so many that I enjoyed. Generally the first film in the most popular franchises (The Matrix, Predator, Aliens, Star Wars, Star Trek, Terminator, etc) as well as one offs like Ex Machina are films I enjoyed
I have never seen an alien, as far as I know. I do believe there is intelligent extraterrestrial life. I would absolutely pay to board a UFO and go to another planet especially one with superior technology (and hopefully behavior).
From the link you provided @Stefan I discovered Son Of Ingagi (1940): the first all-Black horror film. I will watch this on my TV later -- Thanks!
I watched most of the other films, most of them I did not care about very much. I did enjoy seeing Black Panther, but thought The Matrix was a far better film.