Best Smartphone Which Smartphone Has The Best Battery Power?

Which smartphone has the best battery power? - best smartphone

I'm trying to understand, this smartphone has the best battery power to listen to music or watch videos. I know none of them compared to a Zune or iPod video, but I'm curious, what is decent. I had a Hitachi G1000, and the battery would last a day. Now I have a Nokia 6682, which is good, but I think I want a phone to Windows, because I liked the idea. I would rather have one, that less than the G1000, but almost all phones, and I want something that can be new or used outside of eBay at $ 275. Suggestions?