Why do I want iTunes Match? What are the benefits?

Maybe you don't. Why do you think you might? If all you want is to keep copies of all your music from any source in iCloud so you can play it back from any device you own then Match might be for you. If you want to extend that to include any music Apple owns too then Apple Music would be better for you. Match is cheaper than music if you're thinking on an annual scale. If you don't care about using iCloud for music then getting neither is cheaper ($0).

There could be a few other reasons for getting Match but this is about as far as I am going to take this without you providing more details. ;-)