Best backend language for a membership website

Hey guys,

What would be the best programming language or framework to use for a website where users can create profiles and fill in information? It has to be flexible enough to allow future modifications (to add new features to the website).
Someone told me that he can do it using Wordpress, what do you think? Others suggested Ruby on Rails.

Many thanks!

WordPress isn't a language bra, anything works tbh. Just do it and tweak it later if you really need to.

English.