The best MMORPG battleground to this day is still the first battleground in RIFT - The Black Garden. A simple and fun concept.
Copied the description from a wiki:
"
The objective of this game is to gain and maintain control over a 'Fang' found in the center of the map.
- Available for level 10 and above characters
- The closer you are to the center, the more points you score
- You take more damage the longer you hold on to the fang
- Killing opposition scores points
- Average game time 4-10 minutes
- The Black Garden is designed for 10 versus 10"