Outlook, Gmail, Yahoo, Fastmail, iCloud... What do You use?

I'm currently a Yahoo email user, and I've been thinking of switching to one of the "big guys" - that being Outlook or Gmail. But I'm still unsure of which to switch to as my permanent main.

Both have their advantages...Outlook with a 7GB Skydrive feature, and Google with access to all of its services, especially including Hangouts. Google seems safer with two-step authentication, but Microsoft claims Outlook's server-side security beats Google overall. Outlook (in my eyes) is beautifully designed compared to Gmail, but Gmail has a much better app experience in iOS and Android.

So I turn to you guys. What do you use and why? I might be choosing between Outlook and Gmail at first, but don't hesitate to pitch in if you're using iCloud, Fastmail, or some other email service that's worthy of me switching to as my main. Maybe Yahoo is even good enough to stick with?

EDIT: Thanks Verge for featuring this on home page! And thanks everyone for all of your recommendations!!