I'd say Chinjao stomps. Snack is currently featless and the family members below the Sweet Commanders don't seem like anything Gear 2nd Luffy couldn't put up a fight against considering how valuable someone as equally strong as Jimbei was treat by Big Mom. Old Chinjao without his unique skull shape was probably closer to Gear 3rd than 2nd considering Luffy used a new technique to beat him in G3, so Prime Chinjao ought to be at least on Gear 3rd Luffy's level most likely.