I haven't worked much with cocoonjs or appmobi--I'm just not heavily interested in app stores for phones. But I've had a really good time working with clay.io thus far. They have a really nice API (plus a construct 2 plugin) that can handle leaderboards, achievements, and in-app purchases. Not to mention cloud saves.
I have a freemium game I'm prototyping, and it seems most suited to just run in a browser. I've had very favorable performance tests on ipad2 and iphone4s, so it should run alright anywhere. And, really, it can only get better. I haven't tested performance on any android devices yet, so I can't vouch for them. But clay.io fits all of my needs: for the player to be able to pick up and continue anywhere, in-app purchases (good stuff! Don't be greedy!), leaderboards, and achievements so people can share with friends.
So if you're heading towards standalone apps from the AppStore or Google Play, it might not be the route to go. But for in-browser games, they're doing it best as far a I can tell.