First e-mail address I've ever had was with Yahoo. Yahoo used to be my homepage back around in 2008 or so, and would find myself using the site for pretty much anything, whether it be to do some web-search, read news, look for television schedule, or anything else you could possibly think of, so I've decided to sign-up and create an e-mail account as well, so that I'd be able to check on everything from one, convenient place. It was pretty satisfying, actually! Though, eventually, I've started receiving lots of spam messages, which was quite frustrating as they tended to hide more important stuff under their pile. This caused me to look for other services, and wound up with Gmail.
Gmail's amazing, really; it's simple and to-the-point, and their filters seem to work wonderfully without any sort of hesitation. Have created my Gmail profile about five years ago back in 2009, and haven't looked back ever since. Eventually, they've started incorporating more services, linking YouTube accounts, logging into other sites with Gmail account, and much, much more, all of which were very satisfying (well, at least in my eyes).
Along with above, I also have an Outlook address. I've made this one initially so that I would be log into Windows Live Messenger so that I'd be able to chat with friends and whatnot (back then, it seemed to be quite popular), but now that it no longer exists, I mainly use it for Skype. Have never used this one for mails, though, haha.