mermaid.js appears to be gaining popularity, at least by the looks of Github allowing it for inline diagrams. Probably chosen because it's implemented in js...
Anyway, I tried using it to draw out our observabillity collection pipeline at work, and my conclusion is that the topology is super weak. Specifically, I used flowchart, one of the most basic types, but it really is only suited for flows. Lines between nodes force a before-after placement in the graph, meaning there's no sideways lines, and if your graph gets too long, it's weirdly squashed with elements being placed off center. Also lines cross over unnecessarily, and no amount of reording the nodes and edges will get you what you'd intuitively draw.
Looking at their other chart types, I think that's where mermaid's main value proposition lies: charts that need a complex structure and calculations to align properly, which can still be calculated from relatively little code.