For me Hotmail...
EMail notification (with the MSN or the gtalk plugin) in miranda is nice, but it's a little bit useless for me.
Why? The problem is not the notification, but what happens after the notification? It open the Mail website, I am not a friend of this sites. It's okay when I am outside or at work, but at home I maybe sort the mails, set reminders or whatever, or in other words, miranda is no email client.
My EMail client is Outlook 2007. MS have a nice addon for it, it's named "Outlook connector" with this you have Hotmail access and Calendar. (And yes, screen notifications too)
(Okay for GMail I can enable IMAP, but IMAP+GMail+Outlook, ermm, you know what I mean if you ever tried this)
Another point is, that I very often visit MS websites, forums, blogs, newsgroups. Most of this sites have an LiveID login and alerts via EMail and Alerts.
Spam? The spam amount in GMail is much higher.
Sure the gmail spam folder works great, but you get the mails.
I assume the server side spamfilter in Hotmail works a little bit better,
even you don't get spam mails in the spam folder.
(I know that the MS server blocks some domains)