The the Reverse Flash. This is why it's all the more impressive that the first Flash to really put Eobard in his place wasn't Barry Allen, but Wally West.
The Flash is one of the greatest heroes that Central City ever saw, and several men had the honor to wear that iconic red suit. Wally West took over the city's protection after Barry Allen died in the events of Crisis on Infinite Earths, and by all s, Wally was a fantastic hero. He clashed several times with Barry's old villains, and the first time Wally West came face to face with Eobard Thawne, the Reverse Flash, would result in one of the worst beatings the villain has ever gotten. This is impressive considering Reverse Flash is one of the Flash's biggest villains.
Wally West Managed To Completely Humiliate Reverse Flash
Readers got to see Wally's toughest fight yet unfold in the extra-sized issue of The Flash #79 by Mark Waid, Greg Larocque, Roy Richardson, and Gina Going, during the storyline The Return of Barry Allen which saw Barry miraculously show up on Wally's doorstep, after years of being dead. Over time, Wally and the other speedsters, Jay Garrick, Johnny Quick, and Max Mercury, start to notice that Barry isn't the same as he used to be, especially after he almost kills a criminal for calling Wally the Flash, and he even ends up leaving Wally for dead when the latter is caught in a death trap. This culminates in Barry announcing he will destroy Central City for daring to forget about him in his absence, which is when the heroes figure out that he isn't Barry at all, but the ruthless Eobard Thawne, aka Reverse Flash.
Throughout a lot of Wally's history as the Flash, he didn't want to sur or replace Barry, who was his idol. Wally was Barry's sidekick even before he got powers, which demonstrates how close the two were. So when Wally took over the Flash, he wanted to honor Barry's legacy, but not reduce its worth by being a "better" hero. This is a roadblock Wally overcomes when he faces Eobard, the one villain Barry could never really defeat. After Wally finally accepts the role of The Flash as his own, he absolutely destroys Reverse Flash, showing that he is ultimately a bully who only picks on those weaker than himself. When Wally finally finds the power to stand up to him, Reverse Flash is reduced to a blubbering mess of fear and tears.
Wally West Reduces Reverse Flash To Tears
This is something Barry was never really able to accomplish, due to the much more personal nature of his conflict with Reverse Flash. Thawne always felt like he mattered to Barry on some deep level due to the trauma he had inflicted on him, mirroring the twisted co-dependent relationship that Batman and the Joker have. Wally, however, was free of this connection, which is how he was able to go all-out on Thawne, beating Reverse Flash worse than Barry ever could and truly becoming The Flash of his era.