Side-by-side, it's incredibly clear that the newest version is total UX garbage. Monochrome icons were a complete mistake, in basically all cases everywhere. A mix of the Lion color, shape/texture, and spacing, plus the Catalina sidebar, would be the best.

I really REALLY love the Lion icons. Colorful but subdued with only mild saturation, distinctive shapes, strong line borders with very slight halo, and mild gradients to make them pop.