Funnily enough the iPhone 3G (and 3GS) is still my favourite. I kinda thought every design since didnt feel as good in the hand and got progressively worse design wise.
My iPhone 1 I feel is even better. Sturdy as a rock. Little chance of it ever bending. Has enough weight so I can really feel it when I use it (good thing). And the screen/device device is perfect for use as a phone.
Yes I still rock the iPhone 1. 8GB.