Accept ku and CTP. ALL enemy planets have REALLY bad defense and attack, the most on a planet being about 1k attack which a lv20 could get. ANY planet which I post as an enemy you should have no trouble getting though, ask me and i'll tell you exact details if you must.
Gas- Massive- Research: Extremely Abundant -Enemy
Gas- Massive- Research: Extremely Abundant -Enemy
Desert- Very Large- Artifact: Very Abundant -Unoccupied
Gas- Very Large- Research: Abundant -Unoccupied
Desert-Very Large Mining: Average -Unoccupied
Volcanic-Very Large Mining: Extremely Abundant -Unoccupied
Oceanic-Very Large-Artifact: Rich -Unoccupied
Gas-Very Large-Research: Abundant -Unoccupied
Icy- Very Large- Research: Very Rich -Enemy