Im using XDK for my first game. Im getting really good performance on Android and iOS. I get 60fps on my old test devices: iPhone5 and Nexus5.
Im just discovering that plugins, like everyone says, are a complete pain in the butt, but ive just managed to get Chartboost interstitial ads and Google Analytics working in XDK using the cranberrygames plugins... how long they continue to work remains to be seen.
I tried my game on cocoon a while back just to compare, and performance was good on that too. But there was a bunch of stuff broken with the game, I guess because I had been testing on XDK right from the beginning. If I had tested on cocoon from the start too, I would have picked up those bugs of course.
I noticed a couple of C2 games published recently on Android were built in Cocoon (Lunar Mission and Artillerists), so those devs are obviously happy with Cocoon.
One thing I dont like about cocoon is their logo being slapped at the beginning of your game. But thats a minor thing. Im happy with XDK provided ads and analytics continue to work