To be precise, you will be replacing Touchwiz Launcher (TWLauncher) with Nova, not TouchWiz. It isn't straightforward to remove.
You could try Google Now Launcher too. Then furnish your phone with the google apps and dont use the samsung ones, and it'll be fairly close, but you will still have a lot of bloatware, and it will never quite be as fast or responsive as a Vanilla ROM.
Nova is great mind, I've got the Prime version - I even paid for it! I'm not using it at the minute but its smooth and very customisable. Even has themes from Android Lollipop.