Zemo. Because his master plan didn't involve a jar of urine.
I'd argue that Civil War's depiction of Zemo was actually a relatively faithful portrayal of the comic-book character. I mean yeah, he didn't have the purple condom-mask, the mink furs, or the Nazi background - but the motivations for the character were fairly spot-on. Zemo in the comics has always hated Captain America for the hero's role in the death of his father. He's also always hated the Avengers by extension - look at the various Masters of Evil teams he's assembled over the years (most notably in Under Siege and the Thunderbolts team). In short, he blames the heroes for the death of family members, which is basically what MCU Zemo is all about. I think Bruhl's performance also succeeds because he made the character very sympathetic and human. One of comic-book Zemo's key traits is that he's not a complete monster - the dude even tried the hero gig at one point.
I think Zemo v. Luthor is actually a pretty good illustration of the DCEU's failings. It's the same with Superman or Batman (or anything Snyder has done) - the DCEU is great at nailing the superficial elements of these characters. Their iconic appearances, their powers. Where Snyder and co. always stumble is in the characterizations themselves. Look at Eisenberg's Luthor: he has the orange hair and the lab coat - just like the comics. He's a mad scientist and a businessman - just like the comics. They've got all the surface-level stuff down. But what we're never treated to all the compelling pathos that makes comic-book Luthor such a wonderful villain. Where's the deep-rooted inferiority complex and xenophobic contempt of Superman's godlike perfection? Where's his Machiavellian confidence that he's the smartest person in the room? The closest we got was the whole "devils come from the sky" speech, but that's it. I mean I'm all for alternative interpretations of supervillains, but I felt that the core of Luthor's character was missing, and he came across more as a plot device than a fully-rounded villain.
Compare that to Zemo where yes, he is a pretty big divergence from comic Zemo on the outside, but they still kept the roots of the character's motives. His hatred for Captain America and the Avengers over the loss of his family, and the fact that he's arguably the most human and empathetic of Cap's rogues. Honestly, I think Zemo might be one of the few MCU villain successes, along with Grant Ward, Kingpin, and Loki. Zemo didn't need any grand speeches to make him a great villain - all we needed was that final scene where he listens to the voicemail that his dead family left, and that alone makes him a far superior villain to Eisenberg's Luthor in my eyes.