Looks like the UR14500P is (or at least was, originally) a Panasonic battery. Although, I think Panasonic’s battery division is now owned by Sanyo (or vice versa).
Some info:
HKJ’s info:
Rating:
Nominal: 800mAH “minimum”.
“Typical”: 840mAH (which is the rating on the battery sold by intl-outdoor).
At this point, it’s seeming like the UR14500P is the best cell. Expensive, but probably the best.
The UR14500P also appears to be the cell used in the new Zebralight ZL584. Intl-Outdoor has the best price, but it’s a 2-pack. I’ve seen single Zebralight 14500’s on Ebay go for $10 shipped to the USA (from USA).
Also, looks like the Nitecore NL147 and Eagletac 14500 are the same cell (based on capacity).