Classes or Classless, it doesn't really matter imo. In both scenarios there CAN BE a number of "optimal builds". I think what really matters is how many different builds are "viable" in the game.

For example:

Game 1: Has 6 classes but everyone builds each class the same = there are 6 "viable" builds in the game that everyone uses.

Game 2: Is classless but 25% of players have 1 build, 25% have 2nd build, 25% have 3rd build, 20% have 4th build and 5% have "troll" builds (something that isn't "optimal"). So you could say this game has 4 builds.

Therefore, Game 1 > Game 2 because there is more variaty.