I like sphere grids and/or license boards myself. I'm fond of systems that aren't really multi-class per se, but where personal evolution is fluid. Like (as I understand it) FFT?? Job System. In some games, when you multi-class, you may lose some abilities, or take some sort of arbitrarily included penalty. I like GURPS, where character creation and subsequent point expenditures are relatively fluid. Evolutionary if you will.