We are coming to a conclusion for sure. They can both make traps and avoid traps. However, I think Grievous would have the advantage in making traps, simply because of his numbers advantage. Either way, I think they are tactically even.
We should also remember Ventress. If Grievous sees that the Mandalorians are able to outwit him and avoid his traps, he can just send Ventress in to kill MtU.
Ventress... I don't think she will kill MtU. First, she has to get through an army of Mandos all foaming at the mouth for a chance to take her on. If she manages that, she'll be worn out and MtU is no slouch in his Beskar armor. Meanwhile, Fett can still make command decisions for the fleet. Heck MtU could even be killed and Fett would just take command and finish it, blasting Grievous's command ship apart. I feel like these allies present a case of Mutually Assured Destruction.
As for the traps, yeah there's no way around it. Like we've both stated, it'll come down to Grievous's trap in every scenario.
I say whoever gets the advantage leaving that engagement will win the Kaggath.