i was in a similar situation as you and for a large amount of time i wanted to get an o2 flame as it was the most hardcore pda/phone you could get. Unfortunately o2 stopped producing and never gave the option to update the phone to windows mobile 6 which is a VAST improvement from 5. Firstly it depends where you live. I live in Sydney so getting a phone with wi fi isnt that great due to the lack of hot spots so I just pay extra for a data pack. Secondly it depends what you really want from the phone. The best thing about the iphone is the applications you can get for it..without a doubt. However i have no use for them so i didnt get one. My girlfriend ended up buying me a nokia e71 for my birthday and its great, slim lightweight and does everything i want it to, even plays divx with downloadable app or just convert format.
That being said the blackberry is really superior in every way. Better screen and faster processor are the main things that make it better but in general and perhaps most importantly...build quality and reliability. Those black berries are workhorses and are like swiss army knives in phone form. However Im not sure if itll be able to match the ipods versatility as an mp3 player e.g. navigation, bit rating and capacity etc. Once again its really depends on what youll use it for most. That being said you should check out the new range samsung is putting out (only bad thing about them is that they're made by samsung