Another alternative is ZEIT Now 2.0 which is supposed to be cloud-agnostic serverless. It puts a few more layers of abstractions between the developer and the cloud providers.
But i am running express and the config is tiny, just few lines. If you use some cloud db provider for db that you can host yourself (like postgres or mongo in my case). You can move to your infrastructure without any pain.
Mind you using Express is not the "ideal" way Zeit seems to push. It is exactly like with PHP - you are supposed to use simple files and leave routing to webserver. I think they forget that there is no PHP framework that uses this. All of them use the "Front controller" pattern and webserver basically routes everything to it. There must be reason for this.