Cerberus may be closest but the role is quite different, at least by my recollection of BA around 2007. BA, a progenitor of Zero-K, seemed to be dominated by porcwars that have no parallel in ZK. At the core of the porcwars was Guardian as it outclassed all T1 artillery. One of the best ways to break a defensive line was to make your own defensive line and try to finish a Guardian before the other side did. Techning up to the kinds of units that could rival an entrenched Guardian cost about as much as a Guardian itself.
The Guardian was removed from Zero-K very early on, back when it was still called Complete Annihilation. There was initially a structure called the Trebuchet that was essentially a static Impaler, the idea being that pure anti-structure artillery won't suffer from the same problems. I don't recall how well it worked but we eventually decided it wasn't required.
Cerberus is heavier than Guardian but overall I would say it is weaker. It costs more, has to compete with factories that can build mobile heavy artillery from the start of the game, is fragile, and has a grid requirement. The grid requirement is there because we're still worried about it being rushed.
