Minecraft 17w43a, Minecraft 17w43b
macOS 10.13.1 17B45a
MacBook Pro (15.4-inch (2880 x 1800), Late 2016)
The GUI scales available now are very dramatic and none are very useable.
In 1.12.2, Normal scale gave buttons that were approximately 10mm tall. In 17w43a, Normal scale now gives buttons that are about 5mm tall. All the scales see the same changes except Auto. Auto in 1.12.2 uses the "large" scale (for better or for worse) in 1.12.2, however in 17w43a, the buttons are even larger.
The following screenshots fill up a 15" laptop screen, in windowed mode. To me, the 1.12.2 Normal view is the most easily read view.