Yahoo! Mail is very fast in delivering and receiving mails. It is the only FREE service that I have found which receives an email as soon as you send it. Also, the overall interface is clean except in some cases where it might be a little cluttered. Just like Microsoft, Yahoo! has tied up email logins with all other services of Yahoo. This means that if I want to chat on Yahoo!, I dont have to make a new account. Another good feature is the automatic bulk mail feature which sends junk mails into a seperate folder.
I would recommend this to all.