I have used the Mogul™ by HTC for five months now, it allows for most busines needs!
HTC Seems like a leader in the smartphones to me.
Buy this one and you won't have to worry about the fixes and bugs with the curent iPhone 3G.
As listed below allows for great productivity in your daily life of a mobile professional could need. Windows Mobile 6 provides several features allowing you to stay connected to your business and personal data on the go. Windows Mobile 6 supports many forms of email, Mobile versions of Microsoft Applications including editing capabilities, and the ability to easily transfer your digital multimedia from your Windows-based PC to your device. It also supports HTML based emails, and includes popular services such as Windows Live Search.
I found the Built-in radio technology for short-range wireless communication works well. When used with your Sprint PCS Phone and accessories, Bluetooth allows fast, secure transmission without cables or wires, even though the two devices are not in line-of-sight. Bluetooth wireless accessories sold separately.