Ahsoka is authoritatively ahead of, and has stalemated a canonically superior version of Maul on a DS Nexus. If that's not sufficient for you, Ahsoka is close enough to Vader, a force user who's feats several years pre-rebels sh!t on maul's, that Vader only bothers to attempt tking her when her defenses are down. So even if you are willing to ignore canon to form an argument regarding sabers, there's nothing stopping Ahsoka from dismissing Maul with the force.
Ant, even if you take SOD Maul as >Rebels Maul in spite of the lack of supporting evidence, trying to argue the gap between SOD and Rebels Maul is bigger than the gap between Rebels Maul and Ahsoka is pure spitballing.
And this is ignoring Ahsoka is shown to be close to Vader, a force user who sh!ts on SOD Maul, even as of LOTS.
Not sure probably a stalemate like their brief fight in Rebels
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Rebels Ahsoka and Rebels Maul were fighting pretty evenly, combined with the quote that he might be the strongest member of the group and his equal/superior performance against the Inquisitors kind of makes me believe both are roughly even fighters. However that's a Maul who's been going around years without a lightsaber fight, has lost his purpose and is far less physically strong than before (TPM, TCW, SoD). So putting in SoD Maul, who's pretty much in his prime, seems to tilt the fight more in his favor.
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This ignores the nexus, and that Ahsoka is authoritatively superior on even ground. Not to mention that even though they were fighting roughly evenly, any edge there was in that duel going to Ahsoka who sent Maul flailing backwards in their first bladelock and then drovehim back.
Maul was troubling the empire, looking for artifiacts, and looking for holocrons. More importantly we have feloni confirming Maul grew and indicating that he became very good in comparison to his tcw self. Not to mention as of Rebels Maul is in the range of a force user who's feats several years pre-prime completely outclass TCW Maul's. There's no reason to think Maul is pot-prime as of Rebels.
Maul wins IMO. As the fight goes on, he's only going to get faster from raging out and that combined with the fact that he's physically stronger, faster and possesses a higher level of ferocity than his Rebels version is enough to give him the win IMO.
force augmentation is a thing yes, dooku had superior physicals to his younger self. As it though, we have a statement saying maul grew as a swordsman and indicating he was very good compared to his tcw self. There's nothing saying otherwise, and rebels maul remains in the range of a force user who's feats several years pre-rebels outclass sod maul's.