With the upcoming Megas Alexandros Tourney (July 22), I figured this topic would be pertitent since it will take place on the Syrian Flats map (a desert map).
Several questions to answer:
1) How much of a bonus does the "Desert Bonus" actually give to such units (that receive the desert bonus)?
2) Which is the best faction that receives the desert bonus?
3) Even with the Desert Bonus, is there enough of an advantage to separate the "desert factions" from the factions that don't receive desert bonuses?
Here are the Desert Bonus Factions:
EGYPT
PARTHIA
NUMIDIA
ARMENIA
As for the best Desert Bonus faction, it seems like Egypt is a no-brainer. Even without the desert bonus, they're already awesome. Plus, every unit in Egypt's arsenal (including the Peasants) receives a Desert Bonus. To top it off, Egypt has access to chariots, chariot archers, bowmen and Pharaoh's Bowmen. In my opinion, Pharaoh pwns the desert!
But as for who's still the best faction to use in the desert (even with the desert bonus), that's a more difficult question to answer.