I'm an Android guy. Here are my reasons (and these are totally subjective to my needs and not meant to be applicable to all users)
I have an HTC G2
1. It has a slide out keyboard. A must for my fat fingers. I can't stand typing on a screen. I even have a keyboard for my iPad because that one is too much for me too.
2. I overclocked the stock 800MHz processor to 1.9GHz running stable at 1.5GHz all day long. Do that with an Apple product.
3. No need to jailbreak to get non market apps. If someone makes an app for an android, you just tell the phone to accept it and you can install it.
4. No constant updates to keep up with which are primarily only pushed to discourage jailbreakers.
5. With the exception of Apples latest hook (siri) an Android device can do ANYTHING an iOS device can do and then some. There isn't anything in the app store for Apple that isn't available either exactly or similarly in the google market.
6. My G2 does wifi calling. When I'm in the Philippines I only have to connect to the wifi in my office and all of my calls get routed from the T-Mobile network right to my phone without any roaming or anything. My outgoing calls go through wifi back to the network and nobody knows I'm not at home. The G2 is one of the only phones that does this and it is a very valuable part of why I love this phone.
7. Android has a hundred different phones with different RAM, processor speeds, options, and sizes. Iphones come in... well... they come in iPhone. Apple likes to think that everybody is the same and they all need the same device. So if you aren't happy with the one you have, then you have to wait till they make a new one to get anything better. And even then sometimes they just put an S behind the model number and throw in some software tweaks that don't really make the phone that much better than what you had before.
8. What is the deal with Apple not putting SD card slots in the iPhone?? That is the stupidest thing I've ever heard of. This is why the Android tablets are starting to rock so much. USB slots, SD Card slots, and every bit as much power as an iPad. Even the market on Android tablets is catching up. My son is saving up right now to buy my iPad from me and I'm saving up to get an Android tablet. The iPad is an overgrown iPod and the limitations are starting to frustrate me.
I'm not saying the iPhone is stupid or anything. But I am saying that it is basically a toy. If it was a true enterprise device then they would offer more features across a wider variety of phone options running the operating system. If you want versatility in your phone, then the iPhone is a bad choice. You have way more options in the Android world. But if you don't care about processor speed, RAM, or anything else like that, and if you really don't want to do research to determine which phone is right for you, then the iPhone is probably a safe bet. It will do everything you want it to do as long as your expectations are fairly low. If you dream of a faster processor or more hardware features then I would avoid the iPhone.