Nice work, KZ! I love that this thread is still going and that you're tackling this area.
I'm torn on the SC4 vs. Cities Skylines debate. I quit playing SC4 probably about 10 years ago, but looking at your screen shots is almost giving me that itch again. I'm with you that the SC4 models are better than the Cities: Skylines models. Particularly in the un-modded versions of either game. Looking at your low density residential neighborhoods is a good reminder of that for me. The color palate is hard to beat too. The richness of the color and textures in SC4 vs. Skylines is pretty shocking considering the age gap. Out of the box, unmodified, I still think it's the better of the two.
I played Skylines as recently as summer 2020. I had all the DLCs and it was heavily modded with transit mods, hundreds of additional buildings, transit stations, etc. A ton of fun and it was stunning. The 12 years of advancement between SC4 and Skylines was most apparent in the transit network simulation as well as flexibility with layouts (curved roads, numerous modes, lot alignment, etc.). But the problem is that in spite of all of the DLC and improvements they've made, there's no equilibrium. Heavily modded cities with high quality video settings look absolutely stunning, but they'll grind even a high end gaming rig to a halt. Vanilla cities still don't really look any better than SC4. I've read for a year or so that Skylines 2 is in the works, but no announcement has been made. I'm all in when it comes to fruition. But for now, it's hard to be SC4.