I have Gmail, hotmail, and yahoo and gmail is the best hands-down. I have the hotmail account since my school has it's own thing through that but it uses the hotmail system, and yahoo I use for fantasy leagues. Yahoo seems to be the best at those from what I've seen.
However, gmail is the best email provider. I love the themes, it handles spam well, the chat works wonders, labels are really nice, and the new lab items have really improved it even more.