Difficulty of learning vote

Hello everyone,

I am kinda new to the forum but just wanted to get some feedback. I have been a front end developer for the past 2-3 years. I am eager to expand and start learning back end web development and a programming language. I am thinking about Java and PHP. I am just wondering if someone with proficient experience at the following languages can give me a rough idea of the challenge involved. Also what is a good order to learn the following. I understand a good bit a JavaScript and I am assuming it is the easiest.

degree of difficulty: 1 being easy and 100 being super hard.

PHP - (1 - 100)
Java - (1- 100)
Python - (1-100)
JavaScript - (1-100)

Any advice would be great

Thanks,

omgjtt