I recommend you sign up for both and use both but have an application like Thunderbird to take care of the emails simultaneously
I use both but i have more preference of Gmail, cause of huge space and spam filter, but there both pretty good
i love gmails spam filter since yahoo's is pretty much worthless but i hate the fact that i cant creat folders on Gmail and since i cant stand when things are unorganized it doesnt help much... that and i had my yahoo account about 3 year before gmail was even herd of...
gmail...it has better spam filter than yahoo, easy to use, fast, and has a large storage...you can attached files up to 20 mb..
I'll have to throw in my vote for Gmail. Primarily because Yahoo's incoming mail servers employ really bad filtering. Many yahoo users don't receive their emails for hours or days because of Yahoo's rate limiting tactics. Also, Yahoo customer service for their mail is 100% non-existant. There's nobody to call, and nobody ever answers emails with a meaningful answer. They always return "canned" replies which in my experience are not even on topic 90% of the time.
Gmail has a neater, cleaner interface that's a pleasure to use. Compare this with Yahoo that's quite cluttered. Gmail is also quite stable and feels more secure.
I have been using both gmail and yahoo mail simultaneously and I find no specific difference between them to dump one for the other... Regards, RightMan