I’ve been using D2 for my diagrams for about a month now. The D2 syntax is the most natural to me, but finding online help for Mermaid and PlantUML is easier.
I'm impressed with the grid diagrams too. I'm not sure plantUML has anything equivalent.
It doesnt support all the diagram types plantUML does (for now) but it has the only two i ever used anyway. The tooling seems more robust and modern. I think I have a better chance getting my coworkers to try this one
For VS Code users, there's also the terrastruct.d2 extension that provides language support for .d2 files. It even let's you use the preview feature to watch live changes!
If anyone is interested, it would be great to have a write up on d2 and the extension over at !vscode@programming.dev