I just distinctly remember getting slaughtered by Paladins, and having very few good options to counter.

Note that the Viking Pikemen have a lot of extra HP though.

With non-unique units paladins can only be countered by upgraded halberdier, heavy camels or a huge mass of arbalesters. Monks counter them in small numbers but in late game when they're massed they're almost unstoppable unless you have halb/camel in equal numbers.