Akainu has better feats I think. Tanking a blow from Whitebeard like a bawss.
Sengoku's best feat is keeping Garp down lol. But he also failed to kill Luffy, though he was using Gear 3rd.
BEN
BentleySeitei
Sengoku seems to be around Garp level, but he's probably less powerful. Also he's way past his prime. So I think that the current Fleet Admiral would beat the former one.