This is kinda sad. It seems all my life this same arguement happens, over and over again. When I was a kid, it was atari vs. commodore, then it was betamax vs. vhs, then it was ibm vs. apple/mac, then it was dat vs. cd, then it was linux vs. microsoft...
Guys, you can argue that X gaming system is the best until you die. The truth is that it has nothing to do with how good a system is. Betamax WAS, technically speaking, better than VHS. Atari was, technically speaking, better than IBM. DAT was, technically speaking, higher quality than CDs. And linux is, technically speaking, "better" than Windows operating systems.
But, this is the sad truth. The systems that reach the critical mass of popularity are the ones that win. Most of the time, the winner does it by making their system the most open (only one provider of DAT killed it, only one provider of Betamax killed it, only authorized and paid-licensed hardware manufacturers for all systems other than IBM compatible killed the other systems, other than Mac, who struggled until their system became mostly open). Currently, only the d20 system (I believe) is an open system, all the other systems (HEROS, GURPS, ETC) are closed systems. If you want to add on or change those systems, I believe (and I could be wrong here), you have to pay a licensing fee to someone. Those systems will, in the long run, die (it will be a slow death, to be sure). Or, perhaps they will adapt, and become open systems also.
It really doesn't matter if non-d20 systems can do things better than d20 systems. If they stay closed systems, and they let d20 get too far ahead in popularity, eventually they will die.