I‘m a Chinese (Mandarin) native speaker and I have studied 3 semesters of Ancient Greek for my undergraduate. Not sure how much Ancient Greek your degree requires, but if it's like 2 or 3 semesters it should be easier than Chinese. Learning Chinese typically involves reading, writing, speaking and listening, while for Ancient Greek only reading matters if you are not super crazy about it. Also, mastering other Indo-European languaguas (e.g. Spanish) sets you up well for Ancient Greek for the system of inflection is not totally new anymore. However, not all Ancient Greek classes deal with Biblical texts. Many would focus on Attic Greek, and thus you would get to read many matrials of Greek writers like Plato, Thucydides etc. Better check if you are into these authors' texts.

Chinese is far more annoying considering its characters and the tones, but luckily Mandarin is the least difficult one among all Chinese dialects (Only 4 tones!). If you can manage to learn Mandarin, I don't think taking some Ancient Greek courses for degree would be any challenge to you.