In my opinion your requirements are a little fuzzy. If you're developing a website (no hard database requirements) you could go with something easy as jeykill, middleman or gatsby. If you're developing a web application I would try to evaluate my future needs:

Need #1: Since I don't know what my users will do I need to be agile and quickly adapt to business changes. Tool #1: Rails - the flexibility of RoR is still unbeatable. Especially if you're a startup this is really a timesaver. Furthermore it's no rocketscience to develop a decent frontend on top using React or Vue.

Need #2: Shitload of people will use my site. Tool #2: Elixir / Phoenix has kick ass performance and language and framework are well written and thought through.

Need #3: My whole team are frontend devs who just know JavaScript. Tool #3: Maybe Node.js is for you. In the past I've rarely seen a good Node.js backend project but if you're really disciplined (aka writing a lot of tests) it should be doable.

Need #4: My project is a FinTech and I need to talk to banks. Tool #4: Java/Scala/Clojure since you'll might talk to these services directly and all of the have JVM based SDKs.

Need #5: I'm a microsoft consultant. Tool #5: Well then go with C#/F#.