It is much more advanced in the graphics department, and the the 3Dfx acceleration has to be seen to be believed. However, it is only playable on the most powerful Macs, and a VooDoo card is almost a requirement. That's true, but the engine that drives Unreal is extremely powerful and customizable, so it is used in many other games, like Klingon Honor Guard. Time to spin the wheel again. I think we agree that there is no contest here.
Myth wins hands down.
With its gorgeous graphics and incredibly addictive gameplay, Myth is unchallenged. It spawned an even better sequel that improved on the graphics and made the play more intuitive. And that is about the only complaint one could have with Myth. The learning curve is steep for a game, but it is worth the effort. Playing against opponents over a network is about the most fun you can have with clothes on.