Well, all 40k related stuff is OP all round, there you can have kind of a balance since everyone has their share of bullshit. A girlfriend of mine explained it to me this way: "Lets start from scratch, one WC orc, one 40k orc, both naked, its kind of even since the only factors to consider are biological, even then 40k orc has an edge. Lets raise the bar, technology, another bar, magic/psyker powers and so on, it gets to the point when WC orcs are unable to compare factors with 40k anymore even less keep up with the list of bullshit they can bring to the table. Thats why its kind of irrelevant to make these kind of questions, every 40k faction was created to compete between them, so the designers had really no reason not to keep escalating the shit on their repertoire and give them super powerful capabilities, and it works, barely even bothers you that Space Marines can take a cannon shot to the face without flinching because Orks cant really been driven off from a planet unless you Exterminatus ("Fucking mega nuke it", her words) said planet."