Early Versions

The monstrosity that is Traveller 5 got me to thinking about other game's editions and if the later versions were an improvement.

I only played the colored boxed versions of Dungeons and Dragons a handful of times.

The majority of my D&D time was logged with Advanced Dungeons and Dragons.

I played some of D&D 2e, and was done with it before Compleate Cheate MinMax books came out.  I didn't find this edition to be an improvement on the old familiar AD&D.

I have not played any of the later versions of D&D or any D20 game so I cannot comment.  FuzzyGeff says that 3.5 is much improved and is actually playable.  I'll have to take his word since what I tend to want to do with fantasy breaks the rules badly and he's said so.

I played Hero before there was a Hero System.  Champions 2nd and 3rd edition with Carl and my Cat Series of powered armor.  Those are retconned to be Hero 2.  After I was discharged I played Champions 4th edition (Hero 3) and found it to be identical in outcome but with clearer instructions.  Hero 4 I skipped, but dabbled with Hero 5 long to be appalled.  This was the first rule book I'd ever seen that was elevated from door-stop to bullet-stop (literally)!  This was the standard for too long, overcomplicated game book until T5 came along to make it seem streamlined and transparent.  Hero has since streamlined their core rules and it strongly resembles the old GURPS 3rd Edition (Revised) in concept.

GURPS is the only RPG I've played where the new edition was actually an improvement over the preceding one.  1st and 2nd are functionally identical with 2nd really being a successful errata-cation.  3rd edition soldiered long and rarely failed to accommodate what we were trying to do.  It's an expanded version of the 2nd edition rules rather than a replacement.  The introduction of the Compendiums changed it to 3e(R) and we gobbled up the extra detail.

GURPS 4e scared a lot of us.  In many ways it's only superficially still GURPS.  Core concepts from the original game are still there, optional rules from the compendiums are now standard.  Skills have been consolidated and greatly reduced in number.  Combat with guns has been dramatically streamlined.  While the rules for advantages seem the same, the huge change was rationalizing them based on effect rather than source.  Flying is flying now with modifiers for special effects like wings or using psionics or magic.

Traveller...  Oh my Love what happened?  I started with the Little Black Books.  I stayed with them too since Megatraveller's (T2) universe was teh suxxor.  I skipped Traveller: The New Era (T3) because it was set in the same universe I rejected in Megatraveller and I didn't even look at Marc Miller's Traveller (T4) because it was a prequel to the established universe I was using.  Since I'd converted my LBB Traveller universe to GURPS on my own twice, using the GURPS 3e(R) GURPS: Traveller (GT) seemed natural.  GT and the later Mongoose Games Traveller have something in common; That Megatraveller Shattered Imperium shit never happened because it was fucking stupid; don't break the setting to sell a new rule set!  Mongoose is a system I am gaining familiarity with thanks to questions from Erin, but it's very much AD&D to the LBB's D&D.  I think we've covered the shit-pile that's T5 already...

Hmmm, seems like the 5th edition is where things break...