People obsessing over old results in U18 tournaments are looking at the wrong thing. These prospects all mature at different paces, and peak at different times.
I watched every scrap of video I could for Leo's SHL games and Michkov's KHL games, and I think Carlsson is a better player right now and will translate much better to the NHL. I think the shine on Michkov is coming off vs NHL defenders. He already looks much weaker vs good KHL defenders - his best performances in the KHL were vs players that didn't belong in that league - or for instance the Team China goalie for Kunlun who put up an .815. Small players frequently dominate in KHL scoring and you have to ask how they look vs the best defenses to get a better sense of how they might project to the NHL.
I can see Michkov scoring 40-50 pts per year on an NHL PP, maybe scoring 40+ goals total, but my guess is that people are going to be very disappointed in his overall value even if the points come. He doesn't have the skating or strength to carry the puck vs good defenders, he's not going to carry a team like Kaprizov can. He'll be more situational. I could see playstyle and value somewhere intermediate between Kucherov and DeBrincat but with worse defense. It's also still an open question how Michkov fits in to an established offense where the puck doesn't run through him.
Leo Carlsson is one of the safest bets to be an all-around #1C that you'll ever find. And I don't think his upside is lower than Michkov's either. There's no category where I'm pulled towards Michkov here.