Ok, we get this question fairly often. The really quick answer is: go with IMAP.
But let’s go over what these two email protocols are and then you can decide which is best for you.
POP3 (Post Office Protocol version 3) is not quite as popular of the two protocols. The way POP works is that a single device connects to the server, downloads the emails from the server to the device and removes the emails from the server. Depending on your email client (the software you use to access your email, such as thunderbird, outlook or mac mail), you may have the option to “leave a copy of messages on the server” for x number of days. This is a work around to allow you to download email to multiple devices.
POP can be useful if you are a very heavy email user and you foresee issues with reaching your mailbox or hosting account storage quota.
IMAP (Internet Message Access Protocol) is definitely the protocol we see used the most. IMAP was built to allow multiple devices to manage an email account, with the messages being stored on the server. This is great if you want to use your email account on your phone and your workstation plus your laptop.
Just note that if you delete a message on one device, it will be removed from the others as well.
The caveat with IMAP is that due to the messages being stored on the server, you need to pay some attention to your mailbox and hosting account storage quota.