From Samsung Galaxy S4 Review (Video) | MobileSyrup.com
- The Galaxy S4′s keyboard, despite being powered by SwiftKey, is nowhere near as good as SwiftKey proper. This boggles my mind, as there was every opportunity to make this the truly best native keyboard on an Android phone, but alas, you’re still going to want to download a third party keyboard.
I use SwiftKey, you can try before you buy - https://play.google.com/store/apps/details?id=com.touchtype.swiftkey.phone.trial
I also use Hackers Keyboard, it's free - https://play.google.com/store/apps/details?id=org.pocketworkstation.pckeyboard
Neither requires root.
If you really want to go to town on folders and icons, and don't mind losing Blinkfeed and your HTC widgets, go with Nova launcher - root not required.
You can theme and change your entire icon setup, there are lots of free and paid options on that. Search the Play Store for Nova and you'll find the launcher and endless pages of add-ons.