Favourite SF RPG
Hmm...time to look through the bookshelves.
Again, I could easily point to the "Technocracy" Books from Mage: the Ascension, but I'm trying to avoid using that game series for all my answers.
Rifts... I love bits of it, but overall it's an incoherent mess.
Cyberpunk 2020... It was near future sci-fi when I was playing it back in the 90s. Now it feels more like a speculative version of the present, where a lot of current life exists in the game, but there are a few points where our timeline deviated. It still has a special nostalgic place in my heart, but for hard sci-fi...nope.
I guess that might be a question in itself...hard or soft sci-fi?
Firefly/cortex... This has a simple system, and a setting I like, but there's no particular cohesion between them. It feels a bit sprawling, it doesn't particularly capture the feeling I want from the show, it's an all-purpose toolkit with a few components that prompt some ideas. Generally, it has blended into the background of vanilla gaming systems that don't particularly stand out to me.
For a game that does one thing, and does that one thing well, I'd point to 3:16. It's not everyone's cup of tea, but you know where you stand with it. I've had some great sessions with this game.