I had your same issue a couple weeks ago. I had a yahoo account, but in order to use it in mac mail I had to pay $20 or something, which I didn't want to do. I switched to gmail, and hardly ever get on gmail online but manage it through the mac mail. I think it works great and like it better than the yahoo mail I did use, although I do still check that account because its where all my college letters come though (I'm a junior in HS and getting mail from colleges like crazy, but I am sure am happy it doesn't go to my new account, it's soo annoying).
The few times I have gotten on gmail from the web, it IS different than yahoo, and it confused me at first, but I think I like it a bit better, mostly because they handle email conversations like actual conversations, and you see both sides for as long as they go back, which my yahoo didn't do very well.
The confusing part is you have to add all your contacts to your address book on the mac in order for them to work in mac mail; as far as I can tell it won't pull them from the web, just address book. So updating that was a bit annoying, but I've been using it for 3 weeks now steady (I'm a new mac transfer) and completely love it.
So, if I were you, I'd switch to gmail. Although if you just use it through mac mail, that won't change based on what server its through, so if you want to go for hotmail it may not matter.
I hope I helped? I feel like I may have just ranted...
Haha. Good luck. :]