You can add a 3rd person to your analysis. I've had the iPhone 2G then the 3GS and now the 4 and the 4 has the best signal of the 3 by far.
In my experience all the cell phone companies in the US suck. Go to any of their message boards and you'll see the same complaints over and over. The nature of Apple tends to draw a lot of hype from both sides and that certainly spills over to AT&T. Personally, I had zero problems with AT&T when I lived in the south east. When I moved to Denver I just happened to move into a dead zone and would lose calls constantly. I used the mark the spot app and complained a few times and they apparently did something on their end to the point where I can't remember the last time I dropped a call now.
In my experience all the cell phone companies in the US suck. Go to any of their message boards and you'll see the same complaints over and over. The nature of Apple tends to draw a lot of hype from both sides and that certainly spills over to AT&T. Personally, I had zero problems with AT&T when I lived in the south east. When I moved to Denver I just happened to move into a dead zone and would lose calls constantly. I used the mark the spot app and complained a few times and they apparently did something on their end to the point where I can't remember the last time I dropped a call now.