It's up to you! Below are the main differences between the two.
If you're likely to be checking your email from multiple places or devices (e.g. Your computer, a smartphone, webmail while at work), go with IMAP.
If you're only likely to be checking from one machine (e.g. your desktop or laptop at home), go for POP3
Everything sent to your email address is stored on our mail system until you connect and download it with your mail program.
As messages are downloaded to your computer, they are removed from our mail system. After downloading, messages are stored on your computer until you delete them.
With POP3, your messages are kept in one place and you can read messages (that you've already downloaded) when you're not connected to the Internet.
Everything sent to your email address is stored on our mail system until you delete it. For this reason, IMAP is better if you need check your mail from other computers or devices.
Any changes made to your messages (moving them between folders, marking them as read, deleting, etc) will be seen immediately on every computer or device that you check your email with.
As your messages are kept on our mail system, you'll need to be connected to the Internet to read them.