I've been on Verizon for 10 years or so. Mostly due to them being the only company that cared about bringing signal to my small part of the boondocks. I've never had any problems with them, other then the added fees over the years (upgrade fee now for switching to a new phone on new 2 year contact really is only one to be honest).
AT&T now is in my area, but Verizon usually ends up matching them when they have better deals. If AT&T mobile is anything like my internet side of things.....screw them. (Internet kicks off at times for no reason, and it takes up to an hour plus speaking to someone in India if you need anything).
I used the iPhone 4 as my first smartphone. I liked it, but gave Androids a shot the last time around with a Motorola Razr Maxx HD. It's been a great phone. I've never used a case and it's been dropped a lot, including chest height (I'm 6'0") screen first on concrete. Didn't break and just put dings into the plastic bevel edge. However, KitKat OS screwed up my MMS, to include pictures and group messages, to where I have to download stuff manually. From what I read it's just a conflict with the software on the phone. Then just the fact it's old it bogs down sometimes and due to age, they don't care to fix the software issues.
I just ordered the Moto X 2nd Gen after doing some research. It runs pure Android OS, so I shouldn't have the conflict like I did with software. I really enjoyed my current phone minus software problems, so I decided to stick with Motorola. Also the phone has a lot of great features from Motorola on it that I liked and seem to be useful. Also, it's not as tall as the others and you can make it the way you want on Moto Maker (I went Olive back, lemon lime metallic accent, black face) and add your name on it (you'd be amazed on how a name on something deters theft). Also, Motorola coats most of their phones in some type of water repellent. Me working at times in the rain with no option to go inside, comes in handy. Especially since I hate cases.
Of course it's already 6 months old, so not as powerful as newer phones coming out and it has a smaller battery. It also doesn't have the top camera, but I'm not a big picture taker. But from what I read on some post-release reviews, it still competes with the newer stuff and Lollipop helped the battery life. I was looking at HTC M9, but passed because of height and the heating issues. I looked at the new Galaxy S6. But it's not waterproof at all and I've never cared for the TouchWiz OS Samsung runs on top of Android from playing with my wife's S4. That and it's mostly made of glass like my iPhone 4 was (it shattered once even with it being Gorilla glass). One reviewer had the glass on the camera already crack from where it raised. The main thing, I didn't want to have HTC Sense or Samsung's TouchWiz OS conflicting with future updates, so I went with a pure Android device. However my wife loves her S4 and ain't in a rush to upgrade. But I'd recommend for sure checking out the stuff the Moto X can do from the added features from Motorola and the fact it's pure Android, which also means it will get updates quicker then some others.
Back to iPhone for a second. I personally found I prefer the Android OS over iOS from Apple. The App stores are virtually the same, at least from what I've experienced. sometimes Apple gets stuff first and maintains some you can't get on Android, but it's never been anything I needed. Android offers more options and flexibility in it's OS. I know a lot of people on iPhones, and when the newer version of iOS comes up, almost all of them complain about it.
Hope I've helped some. I've been doing a tone of research into phones the past 3 days, and I felt like I made a decision that best suited me. I do a lot of comparing when I know I'm going to be stuck with something for 2 years.