I still think the original iPhone was the most innovative because it literally created the modern touchscreen phone market. Sure it wasn't the first touchscreen phone, nor was the idea of a multi-touch screen unique, but it was still one of the phones that truly blew my mind because no one thought that a multitouch screen could come in such a small form factor.
In fact, Jeff Han's TED talk only occurred a year earlier in Feb 2006 and the video wasn't released on youtube until 6 months after that. I remember seeing the TED video and thinking such technology wouldn't be common until at least a few years, yet 6 months later, Steve Jobs announced the original iPhone, and no other phone at the time could even come CLOSE.
So imo, the original iPhone was soooo far ahead of its peers (mostly flip phones at the time and the occasional PDA), it wasn't even funny. The modern day phone continued to still be based on the original form.