Citation managers (also known as reference managers) are tools designed to make your life as a researcher easier.
Tools like Zotero, EndNote, and Mendeley can help you:
Citation managers generally have more sophisticated features that distinguish them from simpler citation generators (e.g., EasyBib, NoodleTools). CITATION GENERATORS ARE GOOD FOR SOME THINGS, BUT CITATION MANAGERS CAN DO MORE. THINK ABOUT RETURN ON INVESTMENT, RULE OF THUMB IS 10 SOURCES OR LESS, MAYBE MORE THAN YOU NEED. HOWEVER, GETTING PRACTICE BEFORE YOU NEED IT ISN'T A BAD THING.
Most robust citation managers will have a lot of the same functionalities. Much of the decision will depend on your personal preferences. You can use a comparison chart to differentiate. Other questions to consider include:
If you'd like additional help making a decision, reach out to a librarian. A librarian can also help you transition from one citation manager to another if you change your mind later.
The most important thing is to choose one and then use it consistently.