if you're already comfortable with javascript, i would suggest express, but if you're totally new to the web dev game, i would suggest something like django or rails as they tend to be more "batteries included" and both python and ruby have less "gotchas" in terms of weird edge-case behavior than js does.

my all-time favorite web framework is actually phoenix, which is written in a newer language called elixir that runs on the erlang VM. this is a slightly more esoteric choice, but it's far from unproven technology (it is used at many companies you have probably heard of), and phoenix has a lot of nice features that i now miss any time i go back to the other choices i've listed here.