IMAP mail protocol stores emails on the server, while POP3 mail protocol stores emails locally on your device (desktop/laptop/mobile)
IMAP is better if you are going to access your emails from multiple devices, such as a work computer and a smartphone. POP3 works better if you are only using one device, but have large numbers of emails. It is also a better option if you have poor internet connection or a need to access your emails offline.
In this day and age where most people access their emails from multiple devices, IMAP will best suit your needs.