Units useful for Rushes?

Click the unit you want and press ALT.
The higher the siege damage for the unit the more dam. But sometimes there is a multiplier by the house icon which represents how much more or less damage they cause. 1.3% is good .5% means less.

People with swords, Samurai German Dopplesoldiers and Axe dudes generally do quite well. Horses really suck at taking down buildings except for the Russian Oprichins. (Those Russian horses tear through buildings, but die quickly in combat.)

Hope that helps.

If you have Warchiefs, then it would be the Aztec Spearman, they have a great siege attack and you can get them really early. Pikeman of course are what the European units have. To win in a rush, either youtube aoe 3 rush or, if you want to know now, the russian, aztecs have the best rush attack in the game that I know of.