Simplistic color tier list:
S: Purple (Eye-catching, majestic.)
A: Red, Orange, Yellow, Blue, Pink (Everything you need to paint a beautiful sky)
B: Green, Brown (What is a sky without the ground below?)
C: Black, Grey, and White (Greyscale is important to any painting process. Really good way of planning out light and shadows.)
D: There are no bad colors. Even Vomit Green is the perfect shade of green for painting grass.
F: Forest Grey. I bought headphones in this shade, thinking the clerk told me they were Forest Green because that makes sense. Forests are green, so it makes sense to name a shade of green after that, but no, it was a slightly dark shade of grey. Go outside, look at a forest, tell me where the grey is. The shade is also too dark to look like convincing fog, so that's not why it's called that.