IMO, Pitch Black is barely science fiction. It's an action/thriller set "in space". The exact same plot could have happened with a train wreck in the 19th century, in the mountains, surrounded by wolves. Or any of a dozen other settings. That doesn't mean it wasn't an entertaining movie, though.

There has to be something about a movie that depends on the scifi element for me to really think of it as scifi rather than just, I don't know scifi-themed. For some reason, I do make exception to that rule when it's functioning as an allegory or metaphor, rather than just window dressing.

So, that said, my favorite scifi movies would be movies like 12 Monkeys, Brazil, Blade Runner, Code 46, Wild Palms, Children of Men, Pi, Primer, Dark City, Strange Days, Unbreakable, V for Vendetta, Gattaca, eXistenZ, Solaris, New Rose Hotel, Abre Los Ojos, Paycheck, Total Recall, Minority Report, Fahrenheit 451, The Andromeda Strain. Unfortunately, very few movies like this get made. (Note: not all of those movies are my favorites, and I don't even like some of them, as I think they failed, but that's a survey of the type of movie of which I'd like to see more be made.)