I think he's probably got a better breadth of work.
Leo has a much greater variety and breadth of work, at the top of his game, than Deniro did. Deniro had a string of three amazing movies early in his career, The Godfather II, Taxi Driver, and Raging Bull, within 5 years, and they're his best work.
Movies like Goodfellas, Casino, and Heat came out over 10 years later, as a sort of Robert Deniro renaissance, and while those were great, they're not "Prime Deniro," they're just great movies that happen to have a very good Robert Deniro in them. He didn't make those great movies like how he made Taxi Driver and Raging Bull great movies. And then the early-90s Deniro renaissance, he really hasn't had a serious role where he's not playing a caricature of his other characters... For the last 25 years, Robert Deniro has been playing a fish-out-of-water-robert-deniro-character in basically every film (and at least one movie where he plays a fish-in-water-robert-deniro-character).
I think his best acting performance since the early 90s run is Silver Linings Playbook, but it's not a leading role.
Deniro, though, took more chances on movies in the 80s... Like, Leo would have never done a movie like Brazil. And so it gives him a solid variety early in his career, but I can't help be clouded by the last 25 years or Robert Deniro movies.