I have been android for years and just bought an samsung S5. (No S6 for me because of the lack of SD card and removal battery). I love the S5 and lollipop.
I also bought an Ipad air a month ago for work and it works well for what I need, but the operating system is so far behind android its really a joke that anyone could compare the two. IOS is really no different than the original IOS years ago, besides adding a few drop down menus it looks and feels like IOS of 2007.
The lack of widgets and ability to customize your user experience is beyond annoying. The lack of a menu and back button drives me crazy. The fact that you have to change the settings for most apps in the setting section and not in the app itself is annoying as well.
For the good: IOS works really well with Apple TV and streams everything smoother than Android, although chromecast is getting better. Apple also syncs better with Itunes than android. but Itunes sucks for the most part.
If you like an operating system with no options or ability to control your own phone, than IOS is your option. However, if you like the ability to customize your own phone and streaming is not that important than android is the best system without a doubt.
Also, if you switch to android from IOS give it more than a week to learn the setup. My wife and brother switched from IOS to android and the first week was difficult and they both thought they made the wrong decision. However, after a week or so they both figured it out and now would never consider going back to IOS. My wife used my ipad and thought it was a joke how old the operating system felt.
my .02