Even though Naruto/Sasuke spam nowadays. They still use their chakra sparingly in battles, especially when it was needed during the war arc to heal (kyuubi chakra) the rest of the Shinobi alliance. Not a drop was wasted.
Sakura. Even with basically no chakra left to heal Sakura was able to keep him a live.
She uses every ounce of chakra without waisting any because of her chakra control. She's one of the few ninjas who actually take great care in how much chakra she's uses even though the has mass amounts.
Sakura was stated to have better control than both Sasuke and Naruto, now she basically uses that for combat. She is the clear choice though I will give a shout out to choji and his clan. They store it all as fat so they can use that crazy butterfly mode
Naruto was able to convert his kyuubi chakra into that matching each of the remaining shinobis of the alliance boosting all of their individual talents to kage levels, and he was able to remotely control the shrouds by blocking projectiles from madara and obito, even Sasuke was amazed at all the chakra he effortlessly controlled. I haven't seen anything that comes close to his feats of chakra control.
well neither should be first then should they? because sasuke has used the TB chakra too. as well as hago's. but hey, guess thats forgotten. sure its more of a feat. to control a beast's chakra and your own as opposed to just controlling your own.