As mentioned repeatedly, the most important thing in Heroes is not the race, but the player themselves. I often play as Necropolis; I started playing Heroes quite a while ago (I remember the heyday of the second part), although mostly against the AI. If you want to know who is stronger, take a two-player map and play as both factions at the same time. In my case, the Orc (Haggish) and the Necromancer (Kaspar) won (there were, of course, many nuances, but nevertheless). I repeat once again, I don't claim that the Orc is always stronger (let's just say that for me, it turned out to be stronger). Regarding build orders and other things, there is a separate thread where a lot has been written. The main advantage of the Orc, in my opinion, is speed and, strangely enough, the Blood Fury skill ;) this applies to the final battle.