1. what sort of things do you want to use the system for?
2. have a look at any of the top 10 or so at www.distrowatch.com
3. checkout the (hundreds of) other threads that have asked basically the same qn.
There's no such thing as best (generally). Its your choice.
If you want an MS like experience, try Mint or Ubuntu to start with.
Remember, it's all free, so you can try as many different versions (known as distros) as you like
HTH & welcome to LQ