I would suggest going with Java to start off. Assuming that you are still in highschool, your computer science class most likely uses Java. This is because it is the language for the AP Computer Science Course taught in most US schools. Java is flexible and runs cross-platform between Windows, Mac, and Linux as well as browser support. Java is also the language for Android. There are several libraries and engines that exist that allow you to make iOS apps in Java too.

Java is a very simple and straight forward language. Once you understand Java, you have the foundation to learn almost all other programming languages. C#/.NET for example is very much like Java as it follows very similar coding patterns, concepts, and is object oriented.

Another reason to learn Java is for Minecraft players, which I know that you play or have played before from one of your old posts. Most servers run on a custom software called Bukkit or Spigot which allows you to write extensions for the servers in the form of plugins. I found Minecraft very helpful in learning Java, as I could easily write something up and see it in action without having to worry about making graphics, making anything look nice, etc. since Bukkit and Spigot plugins are both serverside modifications. However, it all comes down to personal preference for what you want to start out with.