I've got a XOOM and an Asus EEE Transformer. The hardware and performances are basically the same. The Asus one can have a keyboard extension, which is great as it transforms it into a small notebook and back to a tablet, but without the extension, the Asus one is disappointing. On the other hand, the XOOM feels more solid and much less plastic than the Asus, and the dock extension is totally useless. However Motorola doesn't seem in a hurry in fixing the SD card issue and upgrading us to 3.1 (I live in a remote country, north of "America", it takes time to bring anything here apparently)
All in all, it's hard to tell which is the best. If you're looking for an hybrid, go for the EEE. If you're looking for a tablet-tablet, go for the XOOM. I would not consider the Cisco one unless it's geared toward business usage, and your business use Cisco phones.