With the release of GURPS Prime Directive, a discussion started up on another board which I frequent concerning discrepencies between the Star Fleet Universe and Star Trek. The debate got me to thinking...
In essence, the Star Fleet Universe stays as true to the original series as the Next Generation and its spin-offs do, just in a different way; in essence, you've got two equally viable versions of Star Trek here, with the latter only having the edge in the sense that it's officially sanctioned by Paramount. (Actually, you've got three distinct settings, as the FASA version of Star Trek did a fair amount of background development of its own which turned out to be incompatable with both SFU and TNG.)
So I've been wondering: What do people see as the most significant differences between these three settings? What do you view as the relative merits and flaws of each? Which is your favorite, and are there any elements of the others that you'd like to incorporate into it?