Magic imbued the following vehicles/transportation means sentience and commanded them to kill each other till there's one remaining. The given sentience will reflect their rider's character.
I'd say the board. purely because i think its fast enough to just crush its way through all the other gear... astrosled and GR cycle are the only things close enough and even then I'd still edge out the board in terms of raw speed. That said how much of the boards capabilities are purely the boards and how much of it comes from the surfer I leave open to debate. Would the board move as quickly w/out surfer? Everything else is pretty much engineered/tech based besides GR motorcycle.