Poster of the month is more about good well thought out posts..
If its about "good well thought out posts", then for me those who stood out were:
Cheetah - Intelligence and critical evaluation
Hassan - Deep thought, wit and ability to inspire thought, an asset
Osmanthus - Fairness - his skills in making a point, yet appearing impartial
Difficult to decide between the 3 as they all meet the criteria equally, but for different reasons.