My better half is convinced that my job is looking at and interacting with black windows. She can't figure out why I need high end computers when all I did is fiddle with the black windows.

Just dark mode for me. Though maybe I should try mixing it up with neon text colors.

Nope, it's all light theme with comic sans and small caps for me

I only use monochrome (16 shades of gray)

I don't have any colors to suggest but I do have two fonts to recommend.

1. Comic Code is a hand drawn monospaced font that invokes the feeling of Comic Sans without looking bad on modern monitors. I love it. The downside is that it isn't free, but if you're interested,
2. Fantasque Sans Mono is the same idea but free.

These two fonts just make things feel a little more human and whimsical in a way I can't fully explain and I love them.

Also, about color themes, never let anyone make fun of you for using a light theme. Sometimes they're better. It's not so simple as dark or light, some tools have awful light themes or awful dark themes.

Just some more font suggestions, these are not monospaced but just interesting fonts:

1. Atkinson Hyperlegible is a font that is meant to be more accessible but not sacrifice aesthetics. I think it is gorgeous. A great video by Linus Boman on the topic.
2. Input is a font that can be either monospaced or proportional, you can customize it. In the magical future where Elastic Tabstops catch on this font would be perfect.