Age Of Empires 3 is the best RTS I've played.

User Rating: 8.9 | Age of Empires III PC
Age Of Empires 3 is an amazing RTS! It has a great campaign, great skirmish, and a good but complicated scenario builder. I've never played the multi player but I'm sure it's good. You can play for eight different civilizations in skirmish plus the extra civilizations in the campaign. I have to agree that eight civilizations is not a very large number. Empire Earth 2 for example has more civilizations than that. But lets compare how well made these civilizations are:
Age Of Empires 3:
1 or more unique units.
A whole bunch of different units.
Different building looks and some different buildings. Different Home City Shipments
Empire Earth 2: 1 or more unique units
The only difference in units are the unique units - other than that every unit's the same.
I have to say that the Age Of Empires civilizations are much better than the Empire Earth civilizations. The campaign has a better plot line than Empire Earth 2. The maps are also a lot more interesting and there's a lot of them. You can ally with natives. It lags a lot less.