Old thread (2019) and was gravedug, but if anyone's wondering today and needs some help, here's a quick breakdown of 2020:
Python/django is good, a lot of libs/resources out there, but eye-sore to read/code with. I don't know much about this but I can say Django is INSANELY good. Some people have praised flask but I've never used it before.
Node/Deno js is good, easy to understand, can also be an eyesore if doing typescript as opposed to es6. Front-end: React JS is good, flutter is the BiS nowadays (performance) but it's annoying to code. Back-end using express js which is decent nowadays. React native is getting web support in 2020 so 1 codebase for everything, and can combine it with nodejs to get a full scope of 1 language which is pretty neat, but totally trivial.
Java/C# is really good but it's showing it's age now, good if you already know java or if you're working for a company that uses those languages heavily. A lot of documentation is available too, especially for Java 8.
PHP was the goat back in the day but now there's better things. (hint hint reactjs just got routes in 2020 which php had for >decade now). Laravel is a good framework (slightly annoying to code), with Voyager for the admin panel, and it's completely free as opposed to node's dashboards. Remember PHP has A LOT of libs/resources, the most out of everything here, except maybe on par with python. A lot of companies use this, alongside wordpress.
For storage, mongodb/nosql is good nowadays, can either squeeze in some postgres and pair it with sequelize js if doing node/deno ^