"Having 3 nations that will cancel each other out"
Could you explain that? I'm not really sure what you mean?
I think it will be more like Age of Mythology (than Starcraft or Rise of Nations), because they have 4 distinct cultures and they say there will still be cities and technology (as opposed to just tiers).
I prefer 22 nations based on a 'generic' culture (with different art for different regions) over having completely unique sides if it means there will only be four. I think it comes down to a matter of personal preference though, and I can enjoy any sort of game:
Total Annihilation: 2 sides, similar
Age of Empires: many sides, similar
Total Annihilation Kingdoms: 4 sides, unique
Starcraft: 3 sides, unique
Warcraft III: 4 sides, unique
Rise of Nations: 22 sides, similar
Age of Mythology: 4x3 unique sides x similar sub-sides
Ground Control: 2 sides, unique
The number of sides isn't the be all and end all of a game, but it is a big feature for me, and 4 sides is fine by me if they're truly unique and well balanced.