This is a great point. Since he got here, Yoan Moncada has put up 11.2 WAR. He has 2.4 WAR this year, and is essentially playing every day. Kopech has put up 1.5 WAR, 1.4 WAR this year, and after having TJS, and then another injury for a while this year, is working out of the pen because he hasn't gotten enough innings under him to start every 5th day.
Honestly, I think both have incredibly high ceilings, and really are almost identical in how good they COULD be. As of today I think there is no question as to who has been better, and who will be worth more in the short term in Moncada. If nothing else, Yo can play every day, Kopech is still building up. Because of that I don't think there is any question as to who has a better chance of being more valuable going forward, as Kopech has a longer distance to travel to hit his ceiling. He still has to ramp up to being able to pitch 180 innings, which isn't something done overnight. Yoan just has to add back his power, which he has already showed.
Finally, I see no point is getting so upset about this debate that I need to call someone a name, but hey, I guess that is what it is.