Mongoose second is my favorite for character generation, though it's a bit slow for one-off adventurers unless the game-master pre-generates a set of characters.
GURPS has the best lists of equipment and ship design rules, but it can be a bother to adapt the stuff for use under other rules.
I like rules light systems for actual play. I've had the best luck with PDQ#, and although Risus is better for more light-hearted gaming than typical Traveller it works well too. I like the idea of Fate, but it takes a bit more effort to adapt Traveller to it.
Of course I have a lot of fun memories of classic too, from back when it was the only edition.