I don't have either, but the iPhone is pretty awesome. If you plan on using it for the internet, 3G network is really fasted in comparison to other providers, and has great coverage.
First of all, I REALLY dislike apple, they have yet to come out with a cost efficient product, well, except for the iPhone. Its like an 8GB ipod + phone + gps + mobile internet + anything else you want.
Most of my co-workers have iphones, and i initially was very hesitant, but after playing around with a few, I actually really like them. They are also only $200.. my crappy phones replacement is $150 and it is nothing near an iphone.
If I was going to get a new phone, it would be an iphone for sure..
I can't say much about other smart phones, a coworker of mine upgraded to an iphone from a blackberry and is very happy. (It was not a storm)