These threads seem to be focusing attacking strength vs. build requirements, but I would tend to answer from a more personal perspective.

I usually do overrate Chivalric Knights. By that I mean I think they can do too much and end up losing a large number of knights when better tactics would have shifted those losses to cheaper units like spearmen.

Also, I tend to overrate Jinetes when the AI has control. Used properly (player controlled) they can be a great unit, but I've always hated facing the Spanish. But more recently I've handled AI Jinetes surprisingly easily.

Both things reflect more my growth as a player than inherent characteristics of a unit, but really the value of a unit is mostly in how you use it.