I'm using the Pocket Loox from Fujitsu-Seimens. It runs Windows Pocket PC 2002.
I know that battery life sucks on all PPC devices compared to Palm, but the built-in functionality of the Loox is second-to-none. Not only does it have SD/Smartmedia and Compact Flash Type II slots - no bulky jackets/sleeves to add on. Furthermore, the integrated Bluetooth is great for syncing with my laptop and T68i, dead easy to send/receive emails and browse the web.