What diagramming tools do folks use?

I've gotten very tired of fighting the GUI of my company's self-hosted charts.io instance, so I've been looking around at diagramming tools. I saw D2 posted on Hacker News, which seems like an interesting option, but I'm curious if anyone around here has a beloved tool to recommend.

I think my main use-case would be diagramming how components of a software system go together, although sometimes I'm interested in making wiring diagrams and stuff, too. Something that lets you specify overall dimension constraints for diagrams would probably help, since I often need to throw a diagram into a PowerPoint.