The iPhone line on the other hand has all the products on the latest version of the OS even if every phone doesn't support the latest and greatest features
i don't feel like this is a super valid comparison, unless you mention that the iPhone ran like horseshit on iOS 2 onward, and the iPhone 3G always ran poorly. now my wife's 3GS runs like butt on iOS 5. further, all the products are not on the latest version of the OS: the iPhone caps out at version iOS 3, and the 3G caps out at version 4. history suggests that iOS5 is the last straw for the 3GS.
if, perhaps, you mean that all the iPhones currently for sale are on the latest OS, i would point out that all the Nexus phones currently for sale are on the latest OS, and that will be true when ICS is released, also.
a more accurate comparison of HTC and Google's upgrade path to iOS:
the original iPhone used the current OS until it didn't get iOS 4, so from 2007-06 to 2010-06, three years, half of which it ran poorly. you have no options for upgrading for new features even if you wanted to.
the iPhone 3G used the current OS until it didn't get iOS 5, so from 2008-06 to 2011-10, three years and some change, all of which it ran poorly. you have no options for upgrading for new features even if you wanted to.
the Nexus One is using the current Android phone OS until it doesn't get ICS, so from 2010-01 to ~2011-11 or 12, just under two years, all of which ran excellently. you will have the option of installing custom ROMs with ICS features if you choose to.
anecdotal, my nexus one also had the defective power button, but since it had previously been dropped onto the highway from my motorcycle (whoops), it was in too ugly a condition for me to send back to the manu for a repair: i figured repair center drones would return it to me as user abuse, and that they'd be right to do so. since i have the option of rooting the phone and installing a custom ROM, i did so and use an app to power down the phone, and the volume buttons to wake it up.
considering it survived a 75mph bounce and skid on the highway (i had to file down burrs on the metal face), i forgave HTC for the eventual failure of the power button. it is my first HTC phone, but they've sold me on their build quality. my first-gen iPhone was had an unusable crack on the screen that needed replacing after a three-foot drop, and once i repaired that, i found that the impact had also killed the battery, as it wouldn't last longer than half an hour idle, or a few minutes in call.
HTC's build quality despite my abuse, and their vow to not stop hobbyists from rooting Android phones has guaranteed that my next phone will be an HTC again; probably their first ICS phone that supports NFC. my wife's next phone was looking to be an Apple, but now she's frustrated with how poorly it has been performing this last month so we'll see.
last thing, i don't agree with Synerg1y's take, "Ya but u can do more on any build of android than any ios build so the comparison isn't really that fair." while the capabilities of the OS are pretty similar, the fine details is pretty objective: i definitely respect that some people (my wife) just want a simple, option-less phone that also connects to the internet. what i mean is, the feature set does not need be mentioned in the same conversation as build quality (though build quality perhaps need be mentioned in the conversation about feature set).