Which email clients work best with the Mail app?

I have a yahoo account but it seems to be impossible for me to get it to work with mail unless i pay for a premium email account with yahoo. I have been wanting to switch my email address anyways...which client should i create an email account with in order to use the mail application? Thanks

Gmail works pretty well with Apple Mail. You can read this page to learn how to setup Gmail with Apple Mail.

During the mailbox setup, Mail can create an account for Gmail without having to follow those instructions (IMAP) but I believe it sets up a POP account.