IMAP – Is ideal for users who access their emails from multiple devices. Since emails are stored on server, changes made on one device are reflected across all devices. IMAP keeps your emails safe on a central server, which is helpful if your device is lost or broken because backups are available on your other devices.
POP3 – Is good for people who want to check their emails when they're not connected to internet a lot. It saves emails on your device, so you can access them without internet. This is helpful in places where internet is not always available. Also, with POP3, you have more control over how much space your emails take on server.