I prefer Gmail over Yahoo! Mail because it is what most of my friends and co-workers use, so I am very familiar with it. The interface to Gmail is much more user friendly and easy to navigate. A gmail account also comes with 10 GB free space on the server and also sincs to my Android phone device.
Gmail is a preferred email provider. They have many popular services beyond their email service, and just by using your Gmail email log in information, you can also access many of their other services. Keeping that in mind, this causes many of their services to work in tandem with one another, creating a more uniform experience for their users.
Having used Gmail for many years, I may be a bit biased on this issue, but I have had nothing but good experiences working with Google's products over the years, including Gmail. For a free email service, it is fast, responsive, simple to use, and easy to manage. I would probably never switch to another provider.
I prefer Gmail to yahoo for email. I actually use both but Gmail is more secure in my opinion and I use that for financial reasons.Plus Gmail is easier to navigate on my phone. I use Yahoo Mail! to sign up for contest and websites since it's less secure than Gmail.
I realized the other day that I have been using Gmail for about a decade, and I have never had any issue or problem with it. Gmail has a very intuitive interface and is very easy to use, syncing with other google products and searches which I use every day.
Can't even figure out how to send an email in Gmail let alone reply to one. Yes, there is a compose button, but it just blanks out part of the window and doesn't do anything. Plus it has weird little icons all over it that mean nothing to me and moves mail around some weird way other than folders. Of course I prefer the classic Hotmail even better, but Yahoo has most of its features.