Boomkin is really easy and fun to play by hand, but of the ones I've tested I havent found anyone that stands out, it all comes down to how it manages the eclipses and if it does mushrooms correctly etc.
Sometimes its best to be in a certain eclipse before a certain part of a fight, and I think thats the logic most CC's dont have, as they follow the rotation perfectly going from eclipse to eclipse, using tree on cd etc you
may not have the right eclipse for that execute-phase paired with trees that would be optimal etc. Boomkin seems like a bit of a puzzle as far as CC's go, I hope a magician takes a look into it soon ^^