Cycling was the main factor in the switch.
I love Android. I loved my Galaxy Nexus and believe 4.2.1 (Ice Cream Sandwich) is one of the best mobile Operating Systems out there.
After over a year on Android, I didn't really want to go back to the iPhone, but my options were limited.
It's About the Bike
I cycle. I like data. I need data. I used to use a Garmin 305 to track my speed, cadence, heart rate, and GPS position. My 4 year old Garmin worked well enough until it stopped working period. I would use it to record the ride, then I'd upload it to Strava. Strava made the data useful in too many ways to highlight here, but you should definitely check them out.
I could buy a new Garmin 305 on Amazon for $395.00 but that seems ridiculous considering a smart phone has more sensors and can cost less. My phone has GPS, it has wireless technology (Bluetooth or ANT+) to receive data from other biometric sensors, I take it on rides with me anyway and I already use mobile apps on it to track and share what the Garmin captured. Adding the capture stage to the device is the natural next step. Kind of a no brainer, or should be. Ahem, I'm looking at you Android.
With a small computer in your pocket with GPS all you need is a few other external sensors to capture pedal cadence, power, and wheel revolutions for when you're on an indoor trainer or GPS fails. Sounds like something Bluetooth could handle just fine. Especially Bluetooth 4 with the Bluetooth Low Energy (BLE) feature.
You can very easily do this with an iPhone and some help from the people at Wahoo Fitness.
Chips with No Salsa
My Galaxy Nexus has the same Bluetooth 4 (BT4) chip in it that the iPhone 4S has. It should then have the Bluetooth Low Energy feature to work with the Wahoo Fitness sensors. It's doesn't. Android's software doesn't support it (on the Galaxy Nexus anyway). Even if the Android software did support it, I'd have to hope that the people that wrote the application cared enough about the few phone models with BT4 to write the feature into their software.
I would also have to hope 3rd party hardware people (those external sensors mentioned earlier) cared enough as well. As an example, Strava for Android has a setting for one Heart Rate Monitor and no other options. The iPhone version of Strava has multiple biometric sensor options.
Android Just Couldn't Do It
Actually, Android could have, there is no technical reason. Remember, my Galaxy Nexus had the same Bluetooth chip as the iPhone 4S. The problem is the fragmentation in the hardware and software. Developers like Strava have to shoot for the lowest platform common denominator for the Android ecosystem in a sense and there is huge gap in hardware and software support.
Maybe, possibly, the Wahoo fitness hardware made for the iPhone would work for a BT4 Android device. If not, I'm pretty sure they wouldn't find it viable from a money standpoint to make something for the few Android phones that are out there. Same goes for Strava and the other software vendors out there, it can't be viable for them to try to add in the complexity to support so few phones.
Stability in Hardware for the Win
The iPhone has no such issue. It is a much more predictable and stable hardware platform. That stability allows software developers like Strava and hardware manufactures like Wahoo Fitness to bet on the platform with a reasonable amount of risk. Wahoo Fitness has been able to evolve their solutions from the 3GS and newer. They've also been able to support iPads and the iPod Touch because of the stability.
With a stable base to build on, companies have formed and thrived on the iPhone an iOS. Without stable ground, with a system of hardware and software fragmentation, the lowest common denominator wins and the consumer landscape as a whole suffers.
I'll miss Android, but I love not worrying about my Garmin. I love how much easier it is to record, upload, and share my ride data. I switched and won't look back anytime soon.
If you want some great info on how to cycle and train with your iPhone, check out my long time friend Coach Rob. He's an excellent coach and on the leading edge of this transformation from the old technology guard of cycling to the new.