I had an Android last year. I had it get it replaced twice within 1 month. My brother just got the Incredible 3 months ago, he's on his 3rd replacement. His buddy has one and he's on his 2nd replacement.
I switched to iPhone 3GS at the start of the year, not 1 single problem. I bought the iPhone 4 and not one problem yet. Everyone I know who has an iPhone is in the same boat.
You're right, I have no idea why I keep buying iPhones.
Everybody has different experiences.
I loved my iPhone 3G. I gave it to my wife when I got my iPhone 4. With the iPhone 4, I had nothing but problems. I couldn't talk on the phone for more than a few minutes without "FaceEnding", "FaceMuting", or "FaceCalling" a third party from my contact list.
Apple still hasn't fixed the proximity sensor problem -- nearly a month and a half after the phone was released. It would appear that they don't have a software fix for the problem yet or else they likely would've released iOS 4.0.2 to fix it instead of making everyone wait with bated breath to see if iOS 4.1 will fix the proximity sensor.
I went to Verizon to get the Droid X after I returned my iPhone 4 for a full refund. I have had a few quirks with the phone (one or two reboots in the past three weeks), but I haven't dropped a single call in three weeks, nor have I had any problems with the Droid X's proximity sensor. Given the choice, I'd rather have a phone that reboots itself every few weeks than a phone that I can't talk on without my face pushing buttons on the screen.
We all make trade offs. People sticking with the iPhone 4 are putting up with proximity sensor issues, or the fact that they have to put a case on their phone due to the "magical design", or they're putting up with AT&T's network in the U.S. I lost Apple's iTunes Store on my phone, but I gained a phone with no case on it that I can hold any way I want without dropping a call. I also gained the best wireless network (in terms of coverage) in the U.S. The loss of the iTunes App Store on my phone was a tradeoff I was willing to make.
P.S. -- I'm not an "Apple hater." I love my MacBook Pro. I will continue to buy Apple computers until such time as Apple's management tells me that I can't use their "latest and greatest" computers the same way I've used any other computer I ever owned (including my previous Macs.)