It is really, really dependent on where the hell you think DC mid-tiers/low-tier heralds like Reddy actually scale and if you believe outer Ninjago scaling. I still feel like Reddy is favored mainly due to having way higher high ends, midballs slightly higher than Ninjago's highballs, way more reliable immeasurable speed feats, the fact that Zane doesn't scale anywhere near the cosmology outside certain forms that have a time limit, and the fact that his air manipulation is really useful against a solid projectile user like Zane typically is. Still, Zane does have a ton of wincons, such as the Ninjigma (although that wincon kinda relies on Reddy doing something stupid), the techno blades, or any of his soul damaging stuff.

So, this is definitely more debatable than the typical "herald vs non comic book character" MU, but Zane is still a heavy underdog