I think Qrow's probability manipulation is not as strong as everyone gives it credit for. Even if it does cause misfortune to others, skilled fighters can still recover from it. Qrow has only been seen in one on one fights twice: against Winter and against Tyrian. I will provide video links for each fight to support my points.
Qrow vs Winter:
https://www.youtube.com/watch?v=v5gzPlULCG0
Now, I know Qrow is drunk in this fight and not at his full potential, but that's not the point. Throughout the entrie fight, Winter is able to hold her own against Qrow and there never really seems to be any obvious misfortune that happens to her. If Qrow's Semblance is passive, the fact that he's intoxicated shouldn't affect something that continues to work without his active control. The possibility that it is dampened by his inebriation exists, but considering that Qrow still has enough physical prowess to keep up with Winter while drunk, his Semblance should not be weakened to a point where it doesn't have an effect.
Qrow vs Tyrian:
https://www.youtube.com/watch?v=AadJxdYQR-M&t=213s
Now, we know Qrow is sober in here and at his best while fighting Tyrian. Here, his misfortune only acts twice, once with the building and the other when Tyrian falls through the roof. But even when he falls through, Tyrian still has enough skill and reaction time to grab Qrow before he hits the ground. And inside, Qrow gets the worst of the exchange, as he is thrown through the wall. Now, ultimately, Qrow only loses because he gets distracted by Ruby, but the only time he managed to hit Tyrian once he was disarmed and switched to punching.
It seems, based on the evidence, that Qrow does not have the power of Domino or Black Cat like it seems the arguments before are implying.
Now, onto Guts. Let's say that Qrow's bad luck can cause Guts some problems during a fight. Guts is used to having all of the odds stacked against him and misfortune following him at every corner. By all accounts, Guts should not have survived The Eclipse, his first fight with Zodd, or any of his fights with Apostles, but he had the luck and willpower to overcome the odds. He should have enough skill, like Tyrian, to quickly react to the misfortune Qrow's Semblance can cause.
With Gut's range, skill, adaptability, and broken durability with the Berserker Armor, I'm voting for Guts. I enjoy both Berserk and RWBY, but I feel Guts would eventually win.