Use this combo to kill anyone
FULL UPGRADES
Infantry/Acadamy
Slingers
Skith Chariots
Priests
Siege Weapons
Why?
If you are attacked by archers, Skith Chariots & Slingers will kill them.
If attacked by infantry, yours will kill them.
If there are lots of towers, slingers will knock them down.
Priests are good if attacked by Elephants, and Infantry will take care of Camels / Skith Chariots.
Siege weapons will take out buildings and walls, and help with elephants.
Roman Infantry does well vs Cavalry too!
Weaknesses?
At sea no fire galleys, but all other boats
No good Cavs/Archers
Funny stuff?
Try running a Cav into a group of close together enemy Heavy Cats! (OK, so anyone could do this...)
Romans get almost all upgrades, and cheap buildings & Towers, and logistics makes a barracks worth building. So are Romans the best? Well, it depends who plays. An expert playing Persian/Greek can kill a newbie Shang/other, and an expert Babylonian can kill Phonecian newbies on an Ocean map, and an expert Egyptian can beat a Choson/Roman newbie in an Infantry Only game.