Dutch skirmishers!
With card, advanced armory, and age upgrades they are absolute beasts!
And oh the spamability...as Dutch I can keep up a constant spam from 4 baracks, that's skirmishers being pumped out at 20 at a time! With the church standing army improvement and the fencing school card, not a lot of people can withstand this.
Cavalry is not much of a problem either (unless you haven't been keeping up on your aging).
Falconets arn't a problem either, if you've been upgrading them only one will die a shot do to there not being a bonus. You simply set the skirms to melee to kill them. (Also 40 skirms 1 shot a falconet, which is totally possible, with the Dutch economy.)
The only unit that skirisherss have trouble with are cuirassers, but what doesn't?
Strength in Disipline...
...Disipline in Strength.