As a person that is deeply involved in Kubernetes and Istio, I'm starting to get the feeling that in the beginning, it should be totally acceptable to run containers from Docker Swarm. If your main need is "restart container on error" (which seems likely for startups), you probably can't beat the fast and easy deploy time of Swarm. Also, when the time comes to upgrade to Kubernetes, you won't be locked in to some incompatible solution.

Of course, if you care about scaling, serverless is probably the way to go.