The original SSX by far. It had the most varied, imaginative, and outlandish tracks (favorites being Elysium Alps, Mercury City Meltdown, and Tokyo Megaplex), the best soundtrack, and close-up and bird's-eye views (the former was what I used the most, and the latter was fun every once in a while), which both lacked from the sequels. In that sense, I don't see how Tricky would have been an improvement. Especially when it only had a couple of tracks of its own, which didn't hold a candle to the original batch, and the recycled tracks from the original were too cluttered with all the added candy-colored rails. Not to mention, that the soundtrack was far worse.
EDIT: The 3rd entry was a huge disappointment back in the day, due to its more mundane tracks and open world structure. It was a chore to start up a race because of it.
I wonder how many of those who voted Tricky or 3 have actually played the original, considering it was exclusive to single platform?
Aside from doing all different tricks with all 8 characters, I pretty much "platinumed" the original, eventhough there were no trophies back then.