You're supposed to scale the numbers with the wages, if you want a fair comparison. For the same wages as 40 Swadian Knights you can align 80 Rhodok Sergeants, and in a direct fight, 80 RS would defeat 40 SK. And Swadian Knights are a terrible choice for sieges as well. That's the reason why saying "this unit is best" or "this faction is best" is nonsense...
I'd even be ready to state: for each composition of an army you can name, there exists another composition of equal wages that would defeat the army you named.