I spent soooooooo many hours playing tricky and then twice that on 3.
In tricky I liked Mac and Eddie and Psymon. In 3 I pretty much only played as Mac.
On Tour was alright but they totally screwed the pooch on the map. In 3 you just rode around until you felt like doing challenges. In On Tour you had to pick, is this a free roam run or an event run? It was nice to be able to ski and it was nice that they added computer skiers and boarders on the hill to the mix. I wish they had also added a Need for Speed type thing with the ski patrol. The patrol chases were easily my favorite parts but they only happen in specific events as opposed to just cruising and then there is a patroller on your tail.
TL;DR SSX 3 was the best. Tricky was good for it's time but now shows it's age. On Tour had potential but there were a lot of other things wrong with it.