Banks provide limited amount of gold and honestly, i always needed some plantations.
Ruyters cost lot of coins, same as artilery. Many civs has infartry with bonuses against cavalry (halberdiers, etc.) but ranged cavalry has bonus both against cavalry and artilery, so dragouns, mounted archers/crossbowmen could do the trick.
It also depends on what civ do you use - not every civ can counter everything, f.e. some Native Americans miss cavalry completely and their infartry is just cannon fodder (tupi, iroquois).