I find it too busy, truth be told. Colours pull my eyes in too many directions when I'm trying to read code.
It started because I'm picky when it comes to colour schemes. I'd find one or two things that annoy me and I don't personally have the imagination to fix it, so I'll try to find something else. Or I would get bored of a particular colour scheme and go hunting for something new and fresh.
Removing it took a bit to get used to but now I can't stand going back.
I don't personally subscribe to the Rob Pike idea that syntax highlighting is for babies or whatever, to each their own.
I’ve always thought of any automatic stylistic change as “stylistic highlighting”, so now I’m curious if that’s a rare opinion.
I’m with you that colors can easily start to impede readability. I’m a fan of subtle, judicious color use, so I’ll often start with a palette but knock back the colors from there.
Right now I'm trying out JetBrains mono. I don't really require much from italics but at least some visual distinction. So far I'm enjoying it.
I used Victor Mono for a bit there and I'm still unsure if I like cursive italics or not. They're interesting and fun, but sometimes I think they're a bit too out there, if that makes sense?
My go-to is usually Ubuntu Mono. That might be my favourite font.
Depending upon your motivation for monospace, the iA Writer site offers my current favourite: IA Writer Duospace.
If you want monospace for the crisp, clear, draft-style, clutter-free look when writing code (or similar) then it's excellent. If you absolutely must have every character being exactly the same width then less so as the main difference is that it is monospace for everything except 'm', 'M', 'w', and 'W' which are each 1.5 wide (so it takes two to bring things back in alignment). In practice that is often less of an issue than it seems, and the benefit in readability/clarity/looks (literal mono for those characters makes them compressed) makes it worth giving it a try, even if you only end up using it for Markdown files etc.