One thing people tend to forget about Android and the perceived "lack of updates" is that SOOOOO many core features in Android are updated without a major OS update. Which isn't the case at all with iOS. What I mean is, new features in apps like Gmail, Music, Calendar, Camera, etc. can all be updated pretty regularly just by updating the apps. You want those same things updated in iOS? Then you have to wait for either a point release or an entirely new OS update. Arguing updates between Apple and Android is an apples v. oranges debate. Not one in the same. Additionally, Samsung has shown, at least with the S7/S7 edge, to be on top of the monthly security updates (at least in the carrier versions). All major carrier versions are on the July update.
And I don't believe in the perceived slow down either. My wife had an S6 edge Plus that worked just as well as the day she got it. She only traded it in to get the S7 edge for the battery life boost. But I messed around with that phone, it was absolutely on par with my.