Your also ignoring the fact that benchmarks provide an extremely specific example of what makes one OS better than another. Gentoo might be slightly faster than Ubuntu in respect to how quickly it runs, but thats a moot point if the extra time spent maintaining, emerging and compiling on a Gentoo system outweighs the speedup it provides. Things like ease of use, maintainability, software support, and security should be more important to choosing a system than how quickly it compiles a program (a feature only used by programmers).
But that's a totally different thing
If we want to compare systems and OSes we could begin a conversation and don't finish until the day kernel 22.214.171.124 is out. Here we have benchmarks a nd benchmarks show numbers which are bigger or lower than other numbers. And the benchmarks till now show that Linux is faster than anything else.