I'm feeling an urge to run a #ttrpg next semester, while I'm still on sabbatical and have the time to make this plausible.
Genre? Probably space opera or fantasy.
System? That's the question. I recently ran FATE and I think I want something a little crunchier, more on the "players face the challenge placed by the GM" end than "collaborative storytelling". I'm interested in a good pre-written adventure.
Candidates:
Savage Worlds. I like the level of detail, as well as the use of polyhedral dice, but the settings and adventures I've looked at (Seven Worlds, The Last Parsec) seem dry and vague.
GURPS. Maybe too heavy? The focused Dungeon Fantasy box is intriguing and has good reviews.
Traveller (Mongoose). Again, the adventures out there look very dry. It sounds like you might get through the first two Marches adventures without any combat. I'm not saying I want a mercenary campaign, but action/adventure works better than extended wandering.
D&D 5E. The obvious, easy answer, but overdone and a bit too Hasbro-y. All other things being equal, I prefer skills over classes.
Dungeon Crawl Classics. Fun to be had from the 0-level funnel and spell misfires, but the 1970s-era worldview is borderline problematic.
Nudge me, Mastodon!
You might want to look into Diaspora by Evil Hat Games. It is based on FATE, but with added crunch. Has pretty realistic abstract rules for spaceship combat, military actions, and making game versions of scifi equipment. Also has rules for "social combat", which can be used for political campaigns, espionage, seduction, hostile corporate takeovers, interrogations, and whatnot.
Inspired by Traveller
@nyrath I've played that once -- an intriguing system.
@peterdrake
I've read reviews where the reviewer did session zero with their group. The group became so enamored of the worldbuilding they co-created that the wanted to use it in future game sessions.
*Even if they would play using a totally different TTRPG system*