It all comes down to what you like better. Yahoo! and Google have an equal amount of features. Yahoo! has been around for several years now while Gmail is preety new.

Even though Yahoo! has been around for several years now and is obviously more older than Gmail, they have recently let out their "All New Yahoo!" beta. Anyone who uses Yahoo! Mail is allowed, welcomed & encouraged to try the "All New Yahoo!" beta. Yahoo! has lots of features including "Yahoo! Finace", "Yahoo! Mail", "Yahoo Groups", "Yahoo! 360", "Yahoo! News", "Yahoo! Personals" and many more.

Gmail might be preety new, but Google has been around for so long. As we all know, recently Google has been making tons of software and different technology in all genres and all categories. We all know that Google now has their nose in everything. From softwares like "Google Draw", "Google Updater", "Google Screensaver", "Google Chat", "Google Toolbar" and Google sponsoring softwares like Mozilla Firefox, Picassa 2, Norton, Skype, Star Office & many others. Google also "website softwares" like Yahoo! does. They have "Google Adsense", "Google Groups", "Blogger", "Google Scholar", "Google Books" & so forth.

I personally have both a Yahoo! and a Gmail account, I have the Yahoo! for mail and the Gmail for all of Google features. It all comes down to you, to what features you want, if you want features, or if it's just for mail. Hope this helps, if anybody has anything to add, please feel free to comment. Good Luck!