I have not once ever in my entire life had an e-mail interruption with Yahoo that lasted more than an hour, or my ability to use a different computer to access it.
I'm not saying anything is true, you have to weight each service against the others, even a big ISP doesn't compare to Google or Yahoo, then again services like Google and Yahoo are targeted more often because of this fact.
I wouldn't use Hotmail I've not in the last 10 years been given a hotmail address by anyone I know, but I'm not a mover or shaker or anything like that =) I doubt a lot of people still use it.
If you think any e-mail system is secure, you're wrong. There is no such thing as truly secure e-mail unless you encrypt it and then the fault point becomes the keys used for encryption.
As far as reliability goes any service worth even it's name is going to have 99.99% or better uptime. The 12 hour outages you've had are completly inexcusable, regardless of the cause.
If you're currently paying for an e-mail account through your current company I would complain till my face turned red, that's totally completely inexcusable.