I haven't seen the Meraki software, but what I have seen of the Ubiquiti software is excellent. The UniFi controller does in fact run in the cloud. Granted they could do more on the cloud front in terms of having something pre-built that you can activate with a click.
I'm not sure I'd want my wireless controller in the cloud though, I like the fact that the UniFi controller runs on anything from an 12 core x64 down to a single core ARM board depending on the size of your installation.
There's a significant difference between being able to run software "in the cloud" like how Ubiquiti instructs end-users to install Linux and then UniFi on EC2 and having the entire platform "in the cloud" and ready to use by the end-users with the operational cost rolled into the purchase price/support contract.
Requiring end-users to launch EC2 instances is missing the point of easy to deploy & maintain.
Ubiquiti is working on providing the controller "in the cloud" under the latter model. You can register and use their hosted system for mFi right now. Other stuff is coming.
I'm not sure I'd want my wireless controller in the cloud though, I like the fact that the UniFi controller runs on anything from an 12 core x64 down to a single core ARM board depending on the size of your installation.