If you're writing code in Node.js, I assume you're doing it on a Unix (Mac OSX or Linux) development environment.

If that's the case, I would suggest AWS or something like Linode. While Azure has Linux support, I think you'll probably be better off with a service where the majority of users are using Linux and they have more supported distributions. AWS is probably a better fit there.

If you're writing your node app on Windows, then I would undoubtedly go with Azure since you'll be able to utilize Microsoft support and will likely need it at some point.