I found my big problem with C4 was that it was too rigid to get the architecture quite right, so I ended up either with a diagram that felt overall too low-level (because I'd had to drop down a level to get the relevant details in), or a diagram that was too high level (where I'd just skipped the bits that were with discussion, and now needed to add more written documentation to make up for it).
I really like diagramming, and I tend to do it whenever architecture comes up, but the best tools I've found are just pen and paper (or pen and whiteboard, or in a pinch Microsoft Paint). That way, you can draw exactly the relevant details for the discussion at hand.
This doesn't work great for "diagrams as code", i.e. anything you want to check into git. I've recently had some success with ASCII drawings - there are a couple of online tools that draw the basics, and you can get the fine details by hand - but that's more time consuming, particularly for quick sketches.
I had the same issue as you with C4, and d2 was the perfect balance of simple enough for creating diagrams almost at thinking speed, but with enough features (and growing) that I have been very pleased with it.
I can see having to swap back and forth between levels to pull up technical specifics as mildly annoying. I guess I’ve gotten used to it, either way having a source of truth that multiple roles can consume has been worth it in my org.
If you have smaller or less complicated systems, or your audience is smaller or all peers, then I could also see C4 as having fewer benefits.
I really like diagramming, and I tend to do it whenever architecture comes up, but the best tools I've found are just pen and paper (or pen and whiteboard, or in a pinch Microsoft Paint). That way, you can draw exactly the relevant details for the discussion at hand.
This doesn't work great for "diagrams as code", i.e. anything you want to check into git. I've recently had some success with ASCII drawings - there are a couple of online tools that draw the basics, and you can get the fine details by hand - but that's more time consuming, particularly for quick sketches.