What you probably need to do is start working with permutations of what you've got. Take the bottom section of the first building in the second block, and put it on top of the first building in the first block. Take the top half of the first building in the third block, and put it on the bottom of that building and tweak it so its four pillars. The fifth building in the first block, keep the asymmetrical slope for the center part of the roof, but make the slope around it symmetrical, and change the "notch" on the side to a hole thru the building. Mix 'n' match, use chunks of them as prefab parts for more buildings.

Any time you're dealing with a large set of objects like this, the more different you want each one to be, the fewer options you can create. You're going to have to accept some level of overlap, and find the way to use that to make your work easier/quicker. Once your city is populated with buildings its going to become more "textural" than anything, so it won't matter as much how different they are from one another. In fact, you could make a case that being TOO different from one another might be a detriment in that the really unique looking buildings are the ones that are going to stand [jump!] out the most in a looped sequence, making the loop more obvious than it might otherwise be. You need to find a balance between how different do you want them to be, and not making each building stand out too much.

Really liking the look of your render so far, makes me want to play along. I've been REALLY digging the synthwave/vaporwave aesthetics lately myself.

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