Necropolis or Castle (Which one is stronger?)

Without magic, with identical stats (and hero level), and with the same development pace (it requires not only skill, but also a map that allows angels to be recruited in the second week/archangels in the third week), then the Necropolis faction will definitely lose to Haven and not only Haven, simply because they won't be able to keep up in terms of speed.
Because in Heroes, speed is the most important factor, followed by defense, and then everything else.