Well, that's the direction that both Pre and Post Crisis Brainiacs were heading in when they both ditched the green humanoid look and went fully robotic (Silver Age Brainiac losing the shruken cities motif, and Modern Age Brainiac leaving behind the psychic powers). With a few cosmetic differences, B-13 and Pre-Crisis Robot Brainiac are basically the same thing, so I'd be happy with either one of them, or a combination, being in the movie.
Visually, I think they're both interesting (Brainiac 13 should lose the shorts, though), and the fact that they both have emotions that other characters can play off of definitely puts them above S:TAS's bland version. Without emotions, you can't have such precious moments as Brainiac mocking Superman's punches, saying "I'm sorry, was that supposed to hurt? I'm comprised of a hundred trillion nano-computers. We don't bruise." Still cold and calculating, but his lines wouldn't have to be a boring monotone string of exposition.
And if they could squeeze Lena Luthor somewhere in the movie, incorporating her into the Brainiac plot, then that would be great as well. She made for an iconic moment for both Lex and Brainiac's characters at the conclusion of Y2K, which would more than make up for the lack of depth to Lex in SR, while also giving him the corporate powerbase that most modern audiences associate Lex with.
I think the S:TAS Braniac would be good. He wasn't just the Eradicator though. They showed off more of the evil take over the world kind of program that he was on "Static Shock." Braniac took control of Static's friend and began using the kid's heightened intelligence to scan and digitize parts of earth that seemed unfit. Static's friend could do nothing but watch.