You know, I don't remember anyone here asking this before, and it seems like such a natural question. I'm a little surprised.

It's a tough call, but for me, it'd have to be Disc Wars. As much as I love lightcycles, Disc Wars just seems to bring more to the table as a spectator sport. You have competitors advancing through a series of elimination matches to a showdown with the reigning champion, in one-on-one battles featuring amazing displays of skill and athleticism. And while all competitors are using the same hardware in both 'sports', Disc Wars has the potential for more interesting matchups due to differences in personal ability and combat styles.

I've always been pretty into the Lightcycles more than disc combat, but that's probably because of all the memories I have of playing Tron 2.0 multiplayer. Disc-based combat has always interested me, though, so Legacy's open-canopy lightcycles allowing the combination of lightcycle and disc-based combat was pretty awesome to me.

Light Cycles. They have just enough strategy involved to always be different. Disc combat is usually just everybody spamming the same moves over and over again.