Well I don't know about that Aqua did have to fight Braig then was almost immediately knocked-out by Vanitas so then like you said had to go up against a recently fused Venitas. I'd say Aqua had it harder.
Braig let her win. He only fought to make an diversion so that MX could carry out his plan. Ven had it harder than Aqua ever did to fight within himself. And then have the sacrificial outcome.