True20 is a streamlined, slimed down version of d20 that I think exceeds at providing all the good things you liked about OGL without the excess baggage. The game has only three classes (called roles) and really doesn't need any more, and most things that would be class features are now feats. Magic works like superpowers in Mutants & Masterminds and is pretty open to customization. This particular version (the original) has a section at the back containing sample settings none of which really caught my eye. The newer version has replaced these with the True20 Companion. I recommend that version instead if you just getting into True20.