I second Jaxx if you want to use coins in everyday transactions. The risk is if someone steals your smartphone, or recovery password they will have access to all of your accounts. The most safe would be an offline private key kept in a safe (there is an application to generate bitcoin addresses with a QR code for your private key). Even using Jaxx be sure to store your recovery password in a safe place and consider locking the app with a pin number.

Whatever you do, be sure to secure your private key! Losing that would be like misplacing a debit card with the pin scratched into the back. (Game over)