Basically you will receive biased and stubborn answers to this question.
Both options are very good, but you should choose what is more familiar to you (or if you plan to study with what you like best). In addition, you need to think about the platform on which you will deploy: can you install additional software (for example, libraries) on it? Can you use gem
(Ruby) or npm
(Node.js) to set up additional requirements that you might need?
All this is very relative to you. They are both excellent tools.
Note. Next answer perhaps definitely stubborn.
I would say that Rails, because it could (in my experience) work faster and easier.
In terms of performance, I think node.js might be a little better, but if you don't have a lot of traffic, it doesn't matter.
In addition, do not forget that you are always Unicorn (MRI / CRuby) or Puma (JRuby, Rubinius), and combining these two with nginx , and you are on horseback! Well, on a cougar or on a unicorn, technically ... So, that would solve your performance problem if that happened.
In addition, Ruby (a humanist, afterall) is a much more elegant language than JavaScript, although you can get around its subjective ugliness [1] using CoffeeScript .
In the end, it depends on preferences. I like both, but I prefer Ruby a bit over JavaScript, and I also prefer Rails a bit over node.js.
[1]: I don't find it ugly in person.