I didn't really jump on the Apple rollercoaster though they seem a nice to use and was also aesthetically pleasing product. I needed the mail functionality though.
I might back the outsider today and say I think Blackberry may become more mainstream now they are targetting the consumer market. I'd never tried before but I'm sold on the Blackberry Bold 9000. Does everything well and is very easy to use or add apps too. Mail and sync with Office is reliable and easy. Documents, spreadsheets etc... are easy to read and there are plenty of apps that are of use for many other purposes.
I'm thinking with the new Windows mobile, Apple and RIM Palm may have an uphill struggle.