I'm a CS sophomore and my program teaches both. But I want to go deep on one of them for personal projects and internship prep. Java seems to be where the enterprise jobs are, but C++ gives you more control and is used in games.

Which one will serve me better long-term?

Learn both but go deep on Java first. The job market is enormous and growing. C++ is important to understand but Java will get you hired faster.

If you want to work in games, C++ is non-negotiable. If you want enterprise/web, Java all the way. Pick based on your career goals.

C++ teaches you how computers actually work. Java teaches you how to build things quickly. Ideally learn C++ first for the fundamentals, then Java for productivity.