I'm just getting into web dev, and the amount of choices is rather overwhelming. I know the basics of html, css, javascript, and ruby. I'm trying to decide where I should start devoting my time though if I'd like to move into freelancing, but it's hard to decide which way to go with rails, sinatra, padrino, node, express, tower, ember, and so on.

I can see the value in less or sass, but I'd like to see more details on why you recommend one over the other. Same goes for most of the choices.