My main at this moment are the Dutch and I have to say... The earlier you attack, the better. If you don't take them out Age 3 or earlier...You are screwed. Best Civs that I so far encountered that are pretty unstoppable are the Germans with early game uhlans, and the Brits with green jackets+ Pikemen early game and a heck a ton of grenadiers late game. When attacking, make sure the banks are your top priority.
Bank Boom Baby!