Sorry, but best/top ROM and kernel threads are not really that helpful. The best one will depend on so many different things, like which features of the device you use the most, where you live, etc. It is really best to try the ones available for your device and decide for yourself.
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?