Honestly, the version of Traveller that I use is dependant upon the players I have and what kind of campaign I am going to run. Each version of Traveller has its strengths and weaknesses, most of which have been listed above. I will say that lately I've been using Classic Traveller and d20 Traveller for games with background information supplied by GURPS: Traveller suppliments, extra gearhead and vehicle stuff provided by T4 and TNE, and adventure/plot path ideas from MT. Traveller is one of those games that is like a salad bar, you take what you like and then just leave the rest.
As long as you and your players are enjoying themselves, its all good.
As long as you and your players are enjoying themselves, its all good.