I use mail.com for my personal & pprune email service and am very happy with it.
All free, you have the choice of forwarding your mail to your ISP's mail server (from which you collect your mail as per usual), or you can use mail.com's web based mail service to access your mail from any browser anywhere. Handy if you know you're going to be using internet cafe or someone elses PC for while.
Whenever you change your ISP you simply log onto mail.com & change your forwarding address.
The catch with these services is if they merge or close. You can find you no longer have the mail address you started with. It either gets altered in the merger, or disappears altogether.
In spite of this, I still find it better than an email address that's tied to a particular ISP.