By “ecosystem” I don’t just mean sharing apps - you can now designate up to N (I think N=5?) people as a “family/friends” circle who all share app downloads - but also that iOS devices, be they Mac, iPhone, iPad, and yea even iPod Touch, have built in conveniences to communicate with each other that are very handy. Yes, there are Android equivalents, but they usually come piecemeal, may cost extra to work with your provider, and won’t work with iOS devices unless the user “on the other side” does something special.
Examples: iMessage, FaceTime, Find My Phone, Find My Friends. I use them all the time (well, not FaceTime).
“iMessage” is “just” an Apple iCloud based mechanism for sending text messages - I can still send ordinary SMS text messages (as any modern cell phone can do) to anybody, Android, Windows, or whatever else kind of phone. BUT, because it’s through the iCloud, I can receive “iMessage” texts on all my iOS devices at the same time. I don’t have to have my phone out to answer an iMessage, I can be on my iPad or (if I had one) an iMac. Also, it’s internet cloud based, so I don’t need cell reception either.
Yes, there are other ways to do “messaging over data network” that are not tied to iOS, such as Skype (which is also the “independent” form of FaceTime). But you can’t know that someone else has GOT third party software installed, or necessarily what their userid is on Skype, etc., etc. OTOH, any old person with an iPhone who texts me will by default send me an iMessage.
Same thing with “Find My Friends” - there are independent “locator” apps you can get that cross platforms, but requires you reaching out to your friends/family and making sure they’ve installed and are running those services.
Find My Phone is great too - from any iOS device, I can send out a message to another iOS device to make a binging noise to help you locate it. This is better than just calling the phone, because it could be on vibrate mode - and you couldn’t call my iPad in any case. Further, you can use ANY iOS device, and login to your AppleID to use “Find My Phone” to find your own phone. My kids frequently ask to use my iPad or iPhone to find their phone which is under a pillow or book somewhere in the house.
Bottom line is - for me, my family of five people were all already users of iPhones and iPads for several years when I switched to a Galaxy S4. I enjoyed using the phone, for the most part, but definitely felt “cut off” from the rest of my family.
There is another “configuration” thing about the Android phones that is (or was) pretty fundamental: you can’t restore a phone’s configuration to another phone, even one of the same type. With an iPhone, you can back the phone up, and should you lose or damage the phone and get it replaced, you can restore it - and after it’s done, it’s basically just like your phone always was. If you upgrade your phone to one with a different screen size/resolution (as from an iPhone 5S to 6S) there’s a bit more work involved to rearrange your app icons, but most of your stuff is restored.
With an Android phone, each phone is set up as its own device - if you get a new one, you set that one up all over again. Downloading apps, setting up the icons where you want them, the wallpaper, ring tones, wifi passwords, etc., etc., - you can restore the “address book” and contacts lists, of course, and your email and calendar are on GMail / Google Calendar, but all that other stuff? Do it again from scratch.