I think Gmail is the best email service there is. Tons of features, a generous storage amount, it works with desktop clients like Apple Mail or Thunderbird, and it's free.
I've been using Gmail for what seems like ages. (Does anyone remember that you used to need an "invitation" from a Gmail user just to get your own account?) These days I have several Gmail accounts (actually, some of them are Google Apps accounts—Gmail but with your own domain), some for business, some for personal, and some for junk mail. And even though Gmail works well with desktop clients, it's just not the same experience as the web-based version.
But a few years ago I came across a shareware program called Mailplane that changed everything for me. Mailplane is a small shareware application that gives you all the features of Gmail's web interface via a desktop application. And if you have multiple Gmail accounts, you can manage them all in the same application, without having to sign in and out of your different accounts.
Unlike Gmail, Mailplane isn't free. At $24.95 for a single user license, it's a reasonably priced shareware application that I definitely recommend for any Gmail or Google Apps user. (A family license up to 5 users, and volume licensing for companies or institutions is also available.)
I suggest you give it a try. Visit the Mailplaneapp.com website and download the free 30-day trial. Take it for a spin and let me know what you think.
UPDATE: Coincidentally, Mailplane 2.2 was just released. Even better!