That's a wide open question! Like asking "Can anyone tell me the best type of vehicle?" or "Which type of home is best?"
Besides, people develop very strong preferences even within a given set of moves and disciplines, and don't agree at all on blade choice.
In practice, except for the change from beginner to more advanced blades, you might be cautious about major changes, unless you have money to burn and are willing to give each blade a few months or more to get used to it. For me, a change from MK Dance (7' rocker) to Ultima Dance (8' rocker; much shorter spin rocker curvature and length) was very difficult, but not because of main rocker, which I didn't really notice. Primarily because the spin rocker curvature and length were so different. If money had not been an issue, I should have stayed with MK Dance.
But everyone has different experiences.