There are many good frameworks out there that are a viable choice.
The main reason should be the people you want to hire and how you structure your team. Also, you need to consider if you need high performance or data science
Rails - good choice to start off. Fast to bootstrap a product. If you do not need high performance, you can get old with it otherwise, you will move.
Java Spring - a lot of people know Java
Python - framework is not the fastest and modern, but python is a good skill to have in your team if you need data science
.net mvc -- became an interesting choice.
Elixir Phoenix - smallest community but fun to work with and awesome performance (like .net or spring) will scale very well.
Go/Iris -- best performance and easy to learn. Is missing strong abstractions but an awesome community and libraries.
Javascript (express) - ever changing environment. Your developers can work on frontend and backend. It's an advantage to have just one language.
My favourites are Go and Elixir but in the end, I would decide on the people you will hire.
and there are more good suggestions on that website.