The answer to this question depends on a number of factors, including the type of fish you are trying to catch, the water conditions, and your personal preferences.
If you are catching fish in saltwater or just doing recreational fishing, it is recommended to use a fluorocarbon fishing line. Fluorocarbon fishing lines are less visible in deep water than monofilament or braided fishing lines, so the lure is less likely to scare away fish if you're doing bait fishing. They are also more resistant to damage from saltwater and UV rays.
Experiment with different types of fishing lines and see what works best for you. There is no “one size fits all” answer when it comes to fishing lines. The best fishing line for you is the one that helps you catch the most fish!
No matter which type of fishing line you choose, be sure to get the right size and weight for your needs. If you are fishing in heavy cover, for example, you will need a heavier fishing line. And if you are fishing in open water, a lighter fishing line will do just fine.