I use both gmail and yahoo! But I have more flexibility compared to yahoo mail... Gmail doesn't charge for some extra features while Yahoo charges..
I still use Yahoo because I have used it for many different sign-ups in the past. However, I'm mostly on the Google network--about as much as I used to be on Yahoo.
i used both yahoo mail and Gmail. but i prefer gmail since i have 2 accounts there and i could easily switch user between them. (and yes, i also have 2 Ymail accounts )
It's been my experience though that Yahoo email accounts get hacked far too often compared to GMail. Then once this happens that email ends up spamming me over and over again.
Gmail is best, most speedy, most reliable and too much esay for a new persons. specially i like gmail chat. a very nice way to touch anyone while working.
I started with Yahoomail. I still have an account but new ones are with gmail. Given a choice I would prefer Gmail.
Yahoo is good for making money through its associated free services (Answers, Voices, etc.). Gmail is more bait for getting yourself too dependent on Google, so minimize its use.
From my personal experience, Gmail has been much better for me. Google mail is faster, easier to use, & simply feels more "modern".
I've always used gmail. Its much easier for me, especially as I have an Android. The used interface is better as well. Sky switched from gmail to yahoo. My Nan wasn't happy...