To be honest I've been on Heroku for a long time, but Render looks extremely appealing. Cheaper and more modern. The only downside is they don't have native support for PHP yet... still waiting on that to switch over.
Given the availability of tools like Coherence (www.withcoherence.com) that deliver a great developer experience in your own cloud, it makes sense to evaluate them alongside modern PaaS if you're migrating off Heroku today.
(disclosure, I'm a cofounder of Coherence).