I've never looked at GORE or Openquest, and as far as I can tell Elric and Runequest are the same games in different settings. You can take what you like and throw away the rest, but that's not really my point. Even if RQ has a few variants under the OGL, d20 has Mutants and Masterminds, True20, d20 Advanced, d20 Modern, Gundam, Conan, Pathfinder, Dungeons and Dragons 4E, to name a few (the list goes on I'm sure) not to mention a mountain of supplements supporting its disparate games. It's vastly more popular, and I don't think it's because it's fundamentally a better system. It's solid, I'll give it that much.