I purchased a Galaxy Nexus for two reasons.
1. It has the necessary radio/antenna design to support all the Canadian cell phone carriers and comes unlocked; it's carrier agnostic.
2. It is a "official" Google phone, and gets its software directly from Google (well, once you flash it with the correct Google firmware) so you don't need to worry about having a orphaned product - at least not for quite a while.
Well, three reasons if you count that I needed a new smartphone (my current phones battery was starting to fail since it was over 2 years old). It also aligned with the release of the Galaxy Nexus, so it was the "fresh" new phone at the time. After using it for a while I'm not unhappy with it, but there are a number of aspects about Android that I think could be much much better.
That said, most of the software components of Android are user replaceable (e.g. keyboard, bluetooth voice input app, etc) and if the software that comes with the OS doesn't do what you want, you might be able to find an app that "fixes" that problem for you. Unfortunately iOS doesn't provide this option - if you don't like the default keyboard... tough!