I say that in all but dexterity Canderous is superior, with a great deal of proximity in intelligence and charisma.
For strength, there is no doubt Canderous has the edge. Look at the guy...
Dexterity - with the Mandalorian ideal of heavy armour and heavier weaponry, I would agree that Carth has a clear edge.
Constitution, well, again, Canderous = Mandalorian. And has his implants.
For intelligence, while Carth may be more generally intelligent, Canderous (through dialogue options) displays a clear tactical savvy, seeing and seizing a clear opportunity for a swifter victory.
Wisdom seems quite difficult to assess...neither one strikes me as particularly wise...but then Canderous does seem a little more rational at times, such as when correcting Carth on the blame for Telos' destruction.
For Charisma, I would choose Canderous, if only because he was more interesting a character than the quite annoying and very whiny Carth. HK sums him up best in TSL!
Overall - easy, Canderous.