I am interested to know which phones you have had where you liked the interaction. What did you like about them?
I agree that one-handed operation is critical; that is why I created
Screen Off. Pressing the power button on the HTC EVO 4G with one hand is just not practical, but quickly putting the phone to sleep is something I do dozens of times per day.
I personally liked the HTC myTouch 3G that I had. It was very easy to use with one hand. Of course, it was much, much, much smaller than the EVO 4G, so it was a bit easier to wield overall.
What about you ?