Depends on your needs. I've owned both.
IMHO:
Palm: lots of software, more stable OS, multitude of devices, more "user-friendly"
PocketPC: better integration with Microsoft apps (Pocket Word/Excel), usually more built-in RAM, better multimedia, less stable OS
Whether or not you need extras like an integrated phone, MP3 player, camera, Bluetooth, WiFi, etc. is up to you and your needs. Budget and weight considerations also cannot be overlooked.