We use Heroku because it's easy and fast. We spend 0 time on DevOps stuff (and I've spent a lot of time on that before), and it just keeps running. One click install of add-ons, and consolidated sign on with billing is awesome.

If you're going to use a lot of memory or run many processes it gets expensive fast. But you probably shouldn't use that much memory and you rarely need to run many processes. Heroku will start a new process if one dies (rare), so if you need extreme up time you can pay for running multiples. :)

Their support is stellar even though we don't pay for top tier support. Since we're off timezone wise it might take some time to get responses. But they always connect me to someone with deep technical insights that give concrete feedback and helpful information even when my problems are of the less common ones.