Hey HowToMen, please take a look at this useless but unique app call Home Screen Switcher. This app can set not only launcher app but also any app as home screen, so it will launch chosen app when home button pressed. This app can also shuffle between multiple launcher app, so it will go to one of launcher app randomly when home button pressed.
If you use WhatsApp a lot, check out Timely Cleaner. It's great for getting rid of all those files people share with you but you don't want to keep. They just take up space otherwise. Its got over 10,000 downloads so far.