Been using yahoo mail about a decade now and gmail about four years. I do prefer the interface and ease of yahoo mail, and the way the system works. I don't like the threaded view of Gmail and the lack of true folders.

The other thing I really don't like about gmail (and i DO use about five accounts now) is that when accessing from clients, if I want the email OFF the client, phone or outlook it deletes the mail completly from the gmail. I wish I could just get delete WITHOUT deleting. Although, sometimes I DO like to delete and have it delete. It isn't that big a deal, but I have to constantly LEAVE messages on my phone that I don't want on the phone, but DO want to save in gmail.