Skill trees and Alternate Advancement

[Mirage]

It would be nice if we had a system where you could buy/choose between X number os skills.
And once you choose the one you want, you cannot undo that action.
You'll have to stick with those skills until the end.

That way it would make each player more unique in its on way.

But in the end, the mathcraft will reveal an optimal combination of skills for the least amount of grinding, and people will use this or be considered gimp.