JohnnyDNGRSLY: I think, as many people here will back me up on, the original '94 version. The dynamic MIDI score (do some Googling of "iMuse") is wondrous to behold during a mission.
The '95 Collector's CD-ROM is also worth playing, for the briefing voiceovers and the SVGA in-game graphics.
The '98 edition, while well-intended, I think started to break away from some of the core elements that made TIE Fighter so successful and loved. Again, the music. But also moving away from clean, sharp, untextured polygons and toward muddy, noisy, desaturated textures.
superstande: Okay. Thank you. I'll try the '94 version now. Is '95 version available anywhere..? Maybe GOG's going to offer that at some point?
We're hoping (and there's no shortage of asking, pleading, bribing, and whining going on to that end).
A counter-opinion to Johnny's though: iMuse is, indeed, far better than the CDA score in the 98 edition, and has better audio quality in the voiceovers (there's a mod posted somewhere around this forum that addresses that). However, the 98 version has its advantages:
94 is limited to VGA polygons: think "Starfox". Collectors CD (not available) is SVGA and has nicer textures. 98 is actually rendered, with dynamic lighting and everything (it's cool to see the flash rather than a little puff when you hit something, IMO).
98 is a little harder: the XvT engine really tightened up hitboxes around the various fighters. Whether this is a pro or a con is subjective.
The biggest advantage of the 98 I've found, and why I decided to stick with that version, is that it requires much less derping around to get the most use of my joystick: the throttle works, buttons can be remapped in game (a bit clunky, but less so than messing with dosbox). I might be willing to jump through those hoops for the 95 CD version, but not so much for the Disk version.