If you have a codebase with lots and lots of tests, you are not in a bad place. Remember legacy means a codebase that works and solved and still solves problems over decades. In a sense,a successfull software project implies it will be marked as legacy.
Always prefer legacy over Hype.
A software project being successful doesn’t make the experience of working on it any better. I’d prefer hype if that means I get to avoid suffering with a three decade old C++ codebase, even if it’s not as successful.