There are “many” different flavours of Linux, which are called “distributions”.
If you’re new to Linux it’s a good idea to start with a popular distribution that updates regularly and is widely used. Popular distributions such as Ubuntu and Mint have large user communities, which makes life much easier if you encounter problems.
Testing of Audacity on Linux by the Audacity team is primarily done on Ubuntu or one of its derivatives (such as Mint). Ubuntu is available in several different versions. I am currently using Xubuntu, which I’ve been using for the last few years, and I like it a lot, and bar a couple of minor glitches it is rock solid reliable. There’s no such thing as “the best distribution”, as it largely comes down to personal preference.
What’s not working to your liking in Windows? For a regular user, functionality in Windows is equal to Linux. Where Linux really shines is for power users and programmers. But you can do both and try for yourself. Why not give it a try on a separate partition? A nice distribution is Linux Mint. It’s built on Ubuntu but it’s slightly easier to set up.
I use Xubuntu. Ubuntu, Xubuntu, Lubuntu (and others) all use the same kernel and can run all of the same programs. The difference is the desktop. If you really like fancy desktops, then Ubuntu is for you. Just keep in mind that the fancier the desktop the less memory for running programs. Xubuntu is quite simple and uses quite a bit less memory. Lubuntu uses even less, but (in my opinion) really bland.