Give me something yo use my stack of traveller adv for.Star Frontiers can still be obtained, and I think I've heard someone is working on an updated version or something. (If you hit the Star Frontiers sites, you'll be able to find out for sure, or if it's just a fervent imagination playing tricks.)
And yes, I think a 5th edition rules of the Star Frontiers game would be pretty fantastic!
As to Esper Genesis, I like it better than Starfinder, though Starfinder is getting adventures out faster.
I think if I want to play full on sci fi, I'd go with that new Star Trek RPG, I'm a huge trekkie.
I don't know about the new Trek RPG, but the space combat in the FASA Star Trek RPG was the greatest thing ever!