I actually prefer the Yahoo and Live offerings to GMail (though I have and use all three!). I'm wondering, though, if Yahoo will ever make it out of beta. It's pretty solid, and will be my favourite of all the options if its idiosyncrasies (mailboxes failing to load, for example - not good) ever get ironed out. It would be nice, too, if they'd let me access my account from a POP3 client without having to pay $19.95 a year for the privilege.
-Darwin
Can't you access POP mail if you agree to some Yahoo Spam ?
I have two free Yahoo accounts and it worked fine for me - all the crap came in the same format so it was easy to setup a filter to put it straight in the bin.
Of course things may have changed as I now use an ISP Yahoo account in the UK (which is effectively a paid for account) and use the mail forwarder to send stuff from my old Yahoo accounts to my new address.
That could be another option - just set up forwarding to an ISP based address which you can pick up with POP. IIRC you have the option to leave the original mail on the Yahoo servers so you can then collect in both places but would need to manually delete old mail online.
A final possibility is to use a service like IzyMail (that one is paid but I am sure there are free ones out there too) that grab hotmail and yahoo mail and deliver it via a POP interface to your mail client. This works irrespective of whether you have a paid for hotmail or yahoo account.
You may want to look at this open source project
http://ypopsemail.com/ (note I have never used this as I don't need it but it may be the solution you are looking for). Report back if it works please.