What is the best music software? Not recording software, but software with virtual violins, choirs, pianos that allow chords and have up to date dubstep beats?
If you have a Windows computer, then I'd recommend checking out FL Studio. It's fairly easy to use, and has a lot of flexibility.
As for things like dubstep beats, you may need to import packs or purchase them if they're not included in the latest version, but they should be easy to find around the web if you know where to look.