The amazing $1 microcontroller (2017)
Contrarian view: these days I don't care how much a microcontroller costs. In quantities I'm designing for, it doesn't matter, and the cost is dwarfed by the cost of my time  writing the software.I've spent a lot of time dealing with crappy and broken vendor libraries, erratas, SDKs and toolkits where the vendor changes their entire strategy every year or so, and I'm tired. At this point I wrote (I thnk) three I2C libraries for various devices and systems (they're on github) — I should never have to do that!These days I mostly use Nordic chips — not only does almost every device I design need BLE these days, but the chips are fairly nice, the SDK is developed, maintained and supported, and there is a refreshing feeling of sanity. Sure, a BMD-300 or BMD-350 module with an nRF52832 will be $10 instead of $1 or $2, but I will save so much time and frustration, that it's definitely worth it!A vendor starting to officially support Rust might change my perspective, but to this day I haven't seen any other vendor take software as seriously as Nordic does.