QWERTY or touch?
I came away from this process sure of one thing: There is a mobile device to fit every professional's needs. To find your perfect fit, first consider which of the form factors I've described suits you.
If you primarily communicate by writing, you need a fixed QWERTY device, and in this group, that's BlackBerry Bold or Curve. Spell checking, auto-correction of common typos, automatic capitalization and periods, editable shortcut dictionaries, and ergonomic, intuitive keyboard layouts make every message you send look like it came from your desk. The ability to read and edit Office documents, send and save arbitrary attachments, and transfer files without special software make Bold and Curve ideal choices for people who write. Choosing between these devices could be a matter of style.
A sliding QWERTY device gets you a wide screen and a wide keyboard in one package. Devices like T-Mobile G1 aren't great for writing at length. But their slide-out keyboards can have meta keys that make them workable for things like terminal emulation and remote system management. Their other ideal usage model is interactive browsing. When you need to enter a complex URL or fill in a form, you slide out the keyboard. Otherwise, you navigate by touch screen and trackball. T-Mobile G1 works this combination to near perfection.
A pure touch device is for reading, watching, staying informed, staying in contact, staying on schedule. It's a readout panel for an array of real-time sensors and always-on receivers that you've programmed with your preferences, and access to any of them is at most two gestures away, no matter what the device is doing now. A touch device like iPhone is the tool of a person who always wants to know. iPhone is a poor tool for producing content because it is designed to be the perfect tool for gathering and displaying it.
One thing that all of these devices share is a capacity to entertain. They all play MP3s. All of the leaders here play video clips and have built-in cameras. All let you download and install third-party software directly from the handset. Enjoying a mobile device is not a luxury; it's a necessity even in the stuffiest of business or agency environments. A mobile device is of absolutely no use if you don't carry it, and if you don't enjoy using it, you'll lay it down every chance you get. When you find one that you still can't put down even months after you've bought it, you've found a match.