The iPhone 6 is a much more comfortable device than it’s predecessor, with some nicely rounded edges.
Wait what? A ton of people got their iPhone 6/Plus on launch (like myself) and pretended to like it... But shortly after the Internet was flooded with, "I want to use my iPhone 5S again," and "The iPhone 6 Plus is terrible to hold posts." Oh and the iPhone 6 is obviously more manageable in nature of being smaller, but still, people with smaller hands (not me) didn't like it either way (like my sister).
The roundness is terrible for holding in my and many others' opinions. And I don't feel anything impressive holding a "metal" device if it's so thin it feels like a toy. The M9 nails the feeling of metal, and now with the edges better grip and ultimately having a heft to it.
Needless to say I owned an iPhone 6 Plus for three months and unfortunately had to switch my SIM into my 5S until I was able to sell my 6 Plus. iOS user since 2007, the very first and all it took was the "Alaskan Salmon Grip Edition" iPhone to end it all. Couldn't be happier though.
The only BAD thing about Android for me is there's so many handsets superior to the iPhone I don't know which to buy and like OP, end up with a surplus of phones (albeit a little older phones).
I had a Note 4, Nexus 5, Nexus 6, HTC One M8 and a OnePlus One this last month... It's addicting wanting to get all the Android goodness but being held back by the oh-so-controlling factor of money.
Which takes you to the other "best" part of Android. If you get a Nexus 5 or OnePlus One... You have no difference in software experience than the big boy $750+ phones since Lollipop is so fun, zippy and fluid. In a lot of cases, you even get a better experience. I had a Note 4 but I couldn't handle Touchwiz and even using Google Now wasn't possible because of the disgusting Touchwiz icons. But hey, get a Nexus 5 and you still get an incredible $600 experience (of course with some compromises, mainly battery).
But yes, switching to Android was awesome. I have a Moto X 2014 and a Moto 360, both brand new on the way from Swappa that I bought for $325. Great time to be using Android.