“Science fiction” is kind of broad, most anime has elements of science fiction because the medium (i.e. not being real) lends itself to more fantastical ideas. I upvote others recommendations for steins gate and cowboy bebop, here are some offbeat recommendations.
If you like emotional anime, I really enjoyed Plastic Memories. The last couple of episodes especially really hit me, the running theme of the agency having non-human employees is kinda interesting.
Serial Experiments Lain is a psychological horror thriller type thing with very heavy sci fi elements. Considering it’s from the 90s, it’s commentary on the internet is surprisingly relevant these days. A bit artsy and kind of disappears up its own arse sometimes like Eva, but really interesting regardless.
Wonder Egg Priority is kind of sci-fi, tbh I don’t know where sci-fi ends and fantasy starts, but I really enjoyed it. Just forgive it for the fucking dire ending, I think they ran out of budget, which is a shame. Kind of a “monster of the week” setup with cool action. Killer soundtrack too.
Finally, Eden of the East is a series I’ll always recommend. A mystery/thriller series where a group of people have access to a concierge that can basically do anything and they have a vague mission to “change the world”. Borderline sci -fi because of the heavy use of technology as a plot device. Also has an underwhelming ending, but the rest is top tier.
This, so much. Especially if you cook short grained rice like sushi, makes it almost impossible to fuck up.