I like IMAP, wherever I go, whether using a web mail interface, using Outlook, Mail.app, whatever machine I am on, I always have all my folders, all my mail available to me.
With POP, you can sort your mail into folders, but these folders are only available on your primary machine. Also, unless you set your mail to be saved on the server, you run the chance of having your mail scattered on various machines that you access your mail from. You also have a central location for your SENT items and TRASH as well.
I am a IMAP user & proud of it.