I prefer the Curves of the 3G but the weighted sturdiness of the first gen I like the black back on my 3G it's really sexy, and it doesn't get that dirty like some people say
3G for me without reservation. I like the feel of it, though I keep it in my case more than my v1 iPhone. I'm a bit more protective of my 3G, b/c I haven't quite found the perfect clear acrylic case with a rotating belt clip like I had with v1 iPhone. I like the white outer casing on the back and the ability to receive 3-4 bars at my house with the 3G just frickin' motivates the $#%T outta' me...