What is your go-to PaaS these days?

If you were building a new startup and need to host your core web app, where would you run it to keep things simple?

My inclination is always to do things the fun (hard) way by self managing everything. But as I'm also the one writing the app, that wouldn't be a good use of time.

There seem to be more options than ever, so I'd love to hear your experiences with these tools.