iOS. I've spent way too much time trying to help friends and family figure out their Android phones. My mother-in-law was going nuts trying to figure out why new contacts she added didn't show in her contacts list, and after an hour or so, I was able to figure out some were stored one place and some the other (I don't remember the details) and was able to get all her contacts to show. Now I have a friend trying to get his work mail (Outlook) to sync, and it's a mess.
No thanks. iOS, please.