Former language teacher here
Your mindset going into learning a language makes a big difference. So if you feel pulled towards a particular language, go with that one. You might also want to think about where you would like to travel in the future and what you are interested in. Also, if you like foreign films, books, and music; which ones?
Spanish is more immediately useful in the US because it's a common language here. Employers like English/Spanish bilingual applicants for customer-facing jobs. NB: Spanish in the US is closer to Mexican Spanish than Spanish Spanish. Much of South America speaks some variant of Spanish as well.
French is excellent if you are interested in literature, ballet, cooking, and certain international organizations. It's less awesome for music and film (sorry France). The grammar is not that bad comparatively, but it does have some weird pronunciation rules, which take time to learn. Variations of French are spoken in parts of Africa, several European countries, and parts of Canada.
German is good for reading up on the newest hamster trends, lol. German can be useful in some technical fields. The grammar is more complicated than French/Spanish, but you don't have silent syllables like in French. There's an intense German summer school a couple hours away from me (I didn't go because I opted for a month in Bordeaux instead).
Latin and (I'm assuming you mean ancient) Greek are less immediately useful because they are ancient languages. They are, however, building blocks in many of the modern European languages. They are essential for some of the university-level humanities fields, and I think law and medicine still require Latin. Greek is important if you go into theology. The grammar is more intense than French/Spanish/German (lots of endings to memorize), but you generally aren't expected to hold extended conversations in a dead language.
NB: If you gain proficiency in a modern language, you may have the opportunity when you are at the college level to be a teaching assistant abroad for a year in the corresponding country (i.e. you'd be teaching English to local students). The pay is mediocre, but unlike studying abroad, they pay you (rather than you paying them), so you can afford to rent an apartment and eat.
Edited by Lillias, 01 August 2020 - 04:52 PM.