Tests are generally biased. Unless you're going to run each engine against a weighted distribution of operating systems (as relevant to your existing client bas

Tests are generally biased. Unless you're going to run each engine against a weighted distribution of operating systems (as relevant to your existing client base), on a weighted distribution of hardware architectures (ditto), using your application's library (weighted for real world use, like your clients do) - you're not going to see anything actually applicable. They're still going to be using the browser they use. The only applicable take away is 'module/class/function $x is performing badly in case $y on $environment/configuration $z and we should fix it'. I'm assuming the use case of desktop, browser usage here, and not server usage. Regardless, there is no ultimate $engineA > $engineB that applies globally.