I second Brickwizard's recommendation that there is no best Linux Distribution, picking one depends largely upon your needs, your expectations, your experience with computers, you name it.
I do wholeheartedly encourage you to try out many different distributions, the vast majority of which you can use and try in a live environment from within your USB drive before you install them.
These days, many are suited for low-spec computers, and Linux (in general, there are exceptions) is more beginner-friendly than it has ever been before.
Ultimately, you are the only one that can decide which Linux Distribution is the one for you.