Ask HN: What do you use for modeling

I've noticed myself over the last year adopting technologies that are easily version-ed and transported to other mediums. For example I've fallen in love with markdown+pandoc for doing almost all of my written work.

I run into issues frequently where I need to do some sort of modeling (read UML-ish) and I keep falling back on to Sparx Enterprise Architect (based on familiarity). I've not found any alternative that is open and transportable.

The killer feature in Sparx EA for me is inter-linking artifacts and re-use of entities (like using the same actors across several artifacts for use cases).

I know there are a slew of tools to do these things. I'm curious to know what people use and their rationale.