Not voting quite yet, but I'm leaning towards Sonic.
+ Superior Acrobatics (And it's not even close. He can jump far higher, contort his body to dodge far easier, and can outmaneuver Mario in practically every sense of the word except for flight)
how high can hedge jump? cuz some of Mario's greater jump feats have him clearing
several stories in a single bound
the rest is understandable, but considering Mario is
very well-versed in acrobatics, it isn't as one-sided as you think
+ Item Boxes largely hard-counter Mario's standard power-ups (and vice verse, to be expected from the gaming rivals)
true, some of them counter his standard arsenal, but Mario's also got Optional Equipment here
+ Speed Amps (and not just speed amps, but speed amps so in-character that they're essentially the backbone in Sonic's moveset) that will leave Mario utterly helpless should he enter CQC.
I really don't recall hog using speed amps right off the rip as much as you claim he does
I'm very aware it's pretty in character for him to, considering his reputation and all, but he seems to mainly rely on his natural speed at first
could always be wrong tho
+ Soul Gauge (which grants him not only an additional Speed Amp and another Perception Amp, but grants him endless Resurrection so long as he fills the gauge with energy [which he can do so by simply running, practically guaranteeing Sonic will not face a permanent death])
scan for that speed and perception amp?
also seems pretty inferior to Mario's own array of revives
+ Superior combat skill (Though not by a vast margin. Sonic's capability of fighting and consistently winning against machines designed to either replicate [Metal Sonic, Emerl] or specifically counter [Egg Dragoon] his fighting pattern over years ensures that any adjustments Mario makes in his combat approach with Sonic won't even do any good)
I mean, as of right now, Mario's fought two master martial artists, both of whom become increasingly difficult after each bout against Mario (which is up to 3 times)
Mario's also fought and won against Shadoo, someone who went through the trouble of having Mario battle against 200 enemies (as he had him do the Pit of 100 Trials in Flopside twice), just to get a thorough scan and read on his capabilities and proceed to become Mario to fight him
and lastly, he's fought against Bowser Memory M and Bowser Memory L, both of whom are copies of Mario and Luigi based off of how Bowser remembers the duo, and they're capable of using both of the Bros. own moves against them
so I'd say Mario can relatively hold his own, despite being at a disadvantage
+ BFR with greater range/into Cyberspace (I'm unsure if what Omega is true, but if Mario really can't rewind time after BFR due to leaving said Space-Time then that's another wincon. If it doesn't work, Sealing into Cyberspace like JJ mentioned would work)
true, I don't think any of Mario's rewind options can really save him there, but badges like Pretty Lucky, Lucky Day, and Close Call reduce the chances of that working by quite a bit
+ Danger Sense (Avoids Mario getting any attack off by surprise and further helps Sonic to dodge his attacks)
touché
+ 4x greater reaction speed (which will even out Mario slowing down his perception of time, as Sonic can consistently and repeatedly react to and avoid the V. Maximum Overdrive Attack) + Perception Manipulation of his own (Through Parry, an advantage in and of itself due to how broken it is it works)
I mean, Mario can react pretty easily to both Bowser Memory's utilizing the Super Star, which is pretty consistently depicted to increase speed and more
I'm sure there's other examples, but that's what came off the top of my head
of course though, it still falls short to Sonic's reaction speed
+ Layered Time Stop via Chaos Control (Something that will negate and flip any unfavorable situation Sonic finds himself in, Mario is a sitting duck. This is especially more worrisome for Mario the longer the battle continues).
Those probability badges could aid in buying Mario some time to use some of his other moves, since I don't believe Sonic is dumb enough to try an option that won't work more than once
All of this combined is a LOT to be dealing with.
ye