I played both and basically SSX 3 is the all around better game. But 1080 Avalanche has more detailed game mechanics, meaning that 1080 can be more fun to play. You can try to outrun avalanches which are spectacular and explore the gigantic levels that have scripted events like train wrecks, car crashes, sweeping helicopters, racing skimobiles and other interactive goodies. You can also get unusual boards like the NST rocket board and the NES pad.
The 4 player in 1080 isn't fast paced, it feels like a real race across a vast landscape with multiple braches in the course. In fact, i'd say that 1080 is a cinematic experience while SSX 3 is more of an arcade experience.
SSX 3 is constantly fast paced and very linear, you can also break just about every law of physics. So in the end 1080 is the more realistic snowboarding game, but it wont offer a fast paced racing fix when you need one. SSX 3 will give you that.
Yeah, last I remember, Lazy, you were saying that 1080 was better... you and very few others... :) Okay, I haven't played 1080 so I can't compare. But it's a pretty strong consensus.
As for multiplayer, no matter how bad it is 1080 must have a better 4-player mode than SSX3 because SSX3 only has 2-player multiplayer. Oh well, it's a very fun arcade racing/stunt game...
Yeah, 1080 is more of swnowboarding simulator. SSX 3 is a racing/stunt game. I prefer 1080 as a snowboarding game, but for racing i'll take F-Zero GX in a heartbeat.