I found Golang a pleasure to learn and use. Its minimalism allowed me to pick it up fairly quickly, and features like its baked in documentation allow you to build your libraries as a seeming extension of the language.
If I only learn one right now will I regret choosing Golang over Java?
Java requires a whole app server which is more of a pain to setup. (generally speaking for web dev, think Tomcat, JBoss). It's way more verbose and you really need to rely on the power of an IDE to help code for you, importing class libraries, etc.
Spend a few hours with each, they're very different. Coming from Node/PHP you should be able to pickup Golang faster.