Kinvey looks great, although I wonder if they'll do a Parse and change their pricing model as soon as they go out of beta?
My name is Eli and I run client services at Kinvey (they wisely don't trust me with my own HN account just yet...). While I can't promise that we'll never change any aspect of our pricing (since, as almost all growing companies, we'll almost certainly make at least a few tweaks over time), what I can promise is that we will never lose our commitment to what we've dubbed "success pricing" -- i.e. pricing that is not only compelling compared to the alternatives out there, but a model that directly aligns with a developer's growth goals. That is, our pricing will kick in and increase only when a developer directly benefits, and we feel strongly that this is the most fair and mutually beneficial way to go about pricing any such service (https://console.kinvey.com/#pricing).
Feel free to reach out directly with any additional questions / concerns -- all of my contact info can be found here: http://kinvey.com/eli-lederman