I'm a big Stargate fan, as are most of my gaming friends. I have the d20 version of Stargate, and while it's a nice book, it just didn't have an "oomph" to make me want to play it. I bought it because I thought Stargate would make a great universe for PCs to play in, more so than I ever felt about Star Trek, Star Wars or even B5. Upon buying it, I lost interest, partly because the d20 class/level system it's based on didn't seem to fit the setting, and looked like it would make the PCs unwieldy after 10-12th level or so, and therefore non-stargatey.
I still want to play a Stargate campaign, and Traveller is definitely a better fit for it than d20 was. The MGT career system would fit especially well for Stargate - the careers could define your character right up to the moment you joined the SG program and possibly even after that if desired.