You made the right choice. There. Reaffirmed.
Seriously though, I just came from an iPhone as well. My first smart phone was a Blackberry Curve and it was ok, but it sucked for anything but email and texting. My next smart phone was the original Droid Incredible by HTC. That phone was horrible and I had problems with it from day one but I stuck with it because I thought it was just me not being used to Android. I talked to several other people that had this phone as well and they had so many problems with them that they got rid of it almost as soon as they got it. I stuck with it and continued to have problem after problem for 2 years, leaving a bitter taste in my mouth for Android. Once the iPhone finally came to Verizon, I jumped ship to Apple and got the 4s when I was due for upgrade. I loved it. It was a great phone and I never really had any problems with it. Still, after using it for just over 2 years, I wanted to give Android a try again because it has made great strides since the Android 2.2 days and I just wanted something different for a while. I don't regret my decision. The Galaxy S5 is an awesome phone and the more I use it, the more I like it. I'm not bashing Apple by any means because I still think they make excellent phones, but I was ready for a change.
In regard to the HTC One M8....my wife just got this phone in late March just a few days after it was released. She was a die-hard Apple fan and loved her iPhone 5, but the battery was giving her problems and dying at random times, even with 44% charge left. Sometimes it wouldn't turn on again until it was plugged into a charger. The last thing you want is to be stranded somewhere with an unreliable phone, right? She started looking into what Android had to offer just out of curiosity and when she went to the local VZW store and tried it out, she liked it almost immediately and she bought it right then. She still gets annoyed from time to time because not everything works the same way it did on the iPhone, but she's getting used to it.
I played around with the M8 and I like it a lot. I love the superior audio and front-facing speakers and I like Sense much more than Samsung's TouchWiz interface. The M8 is also a bit heavier, which I actually kind of like and it looks like a premium grade phone. The major drawback and the main reason I didn't get it is because of the "just ok" camera. If the M8 would have had the same camera as the Galaxy S5, I would have gone with the M8. Having said that, I don't regret my decision to go with the S5.