After playing around with color schemes for over a decade and never really being satisfied, I made my own palette that is pretty close to the ANSI color scheme, just with more attractive shades that I copied from things like subway systems and public safety stuff (fire trucks and school busses) since so much research goes into colors being clear and unmistakable in varying conditions of weather or cleanliness. Highlight colors are incremental shades of grey. This has worked remarkably well with 99.9% of default app color schemes. Haven't touched my colors in years now.

Edit:

screenshot: https://imgur.com/a/ZPWjSKk, since terminal.sexy URL sharing wasn't working so well for me. I'd post a desktop screenshot, but I'm on the road and my laptop's WiFi just stopped working, lol.

Some background: cyan is now safety orange. This is because cyan hurts my eyes on a light background and it can be tricky to distinguish from blue, while orange is pretty easy to distinguish from red. IIRC I picked out the shades of blue and magenta myself because most color design documents I could dig up had blue and purple usage paired with a specific background color (usually white) which didn't carry over very well to a dark background. I find these shades to be distinguishable and flexible enough for just about any background color.

The greyscale highlights are generally for tmux and nvim status line background colors, which I use to distinguish cells instead of seperator glyphs.

  [colors]

  foreground = #383838
  foreground_bold = #383838
  cursor = #383837
  background = #aaaaaa

  #black (is black)
  color0 = #000000

  #red (fire engine red)
  color1 = #ce2029

  #green (London underground green)
  color2 = #007d32

  #yellow (school bus yellow)
  color3 = #ffd800

  #blue (Persian blue)
  color4 = #1c39bb

  #magenta (Rebecca purple)
  color5 = #663399

  #cyan (actually "ANSI Z535 safety orange", for my eyes)
  color6 = #ff7900

  #white (from the color white)
  color7 = #ffffff

  ###Highlights###
  # Evenly-spaced increments of the greyscale
  # Makes for good tmux/nvim statuslines
  color8 = #1b1b1b
  color9 = #383838
  color10 = #545454
  color11 = #717171
  color12 = #8d8d8d
  color13 = #aaaaaa
  color14 = #c6c6c6
  color15 = #e3e3e3