For personal e-mails I've used Yahoo, Hotmail, Gmail and a couple different ISPs. My current ISP, Verizon offers tons of storage and pretty reliable service. I can't say much about the e-mail's UI, it works slightly different in each of the browsers I've experimented with. IE is the most flexible but its really fast under Chrome.
I guess the main reason I use an ISP e-mail, I got real tired of the downloading to mostly Outlook. That for me was the most unreliable part of the whole thing, I had more trouble getting my mail than anything else. It didn't matter where the mail was coming from; the trip from Host to Client was fraught with adventure. It got to the point where I was never sure if I received all my mail, I've grown accustom to it being there every time I log in.
That's it in a nutshell.
Hark