Like the original poster, I had decisions to make after leaving Apple. I came from the iPhone 5 and switched after iOS7 or "Bubbles" came out. I did not like the changes in that OS. In addition, I got tired of waiting for Apple to increase the screen size. So I switched to Android and my first was the Galaxy S4. That was my "trainer" for learning Android and as I used to phone I discovered what features I wanted in my next Android device. I don't have many complaints against Samsung. It really was a good phone. One problem was the size of the speaker and the placement. I use my phone as an alarm clock each morning and I have slept through it on occasion. That has NOT happened with the M8, nor do I expect it to. Loud, is an understatement. In addition, on the S4 I used to have to cup the speaker sometimes to make it louder when using some apps. With the speakers facing me on the M8, that is no longer necessary.
And while the screen on the S4 is beautiful and colorful and all that, it is until you go outside. Then, it is almost a complete washout. With the brightness all the way up it is still difficult for me to see the screen. I missed so many outside shots by not being able to clearly see what I was taking a picture of. Not so with the M8. Very easy to see even in direct sunlight. It's beautiful and visible inside as well as outside and I use my phone outside a lot.
Those two things, sound and screen, made me start looking at other phones. I researched quite a bit (much of it here - thanks to all of you who post on this site - very educational) and made a number of visits to stores to try out different devices. Yes, I looked at the new S5. In my opinion, and it is only my opinion, the HTC One M8 stands out from the crowd in so many ways. It is of high quality, beautiful, comfortable to hold, well designed, and has an easy to use UI. For those leaving the Apple ecosystem, this is probably the best device in making the transition.
Is it perfect? No, but what phone is? The M8 is simply heads and shoulders above the rest. If it is not the best phone out there, it has to be in the top two.