So I currently only know english and I'm interested in learning a new language. I want to learn either german or spanish, though I can't figure out which one because I'm not sure which one would be easier and more useful. I know some very basic spanish and absolutely no german. Also idk if this helps or not, but I plan on joining the military. Any advice?
Spanish would probably be the most helpful and easiest to learn in my opinion. You said you already know some Spanish which would make it easier to keep learning Spanish. Spanish is also a tiny bit easier to pronounce and learn. Of course, German has it's perks too and the decision is ultimately up to you, but in my opinion you should learn Spanish.
Well it depends. German would probably be easier to learn grammar wise because due to both English and German being in the west-germanic language family, while the grammar structure of both aren't exactly the same, they're much more similar to each other than Spanish and English are so you'd be at somewhat of an advantage there. Where Spanish may be easier to deal with is down the line where you'll want to practice the language with a native speaker, people who speak spanish seem much more common in the US than people who speak German so if you want to practice speaking with someone, it may be a bit harder to do so even with the Internet. You'd also be at a tiny advantage with spanish by knowing even a little bit of basic spanish to help serve as a foundation for the rest. I want to say Spanish may prove to be more useful but at the same time, I haven't looked into either of the languages to determine which is more useful.