We actually used wkhtmltopdf before we started using pdf-bot. wkhtmltopdf development has slowed a lot, it is very unstable and you need to run a 2 year old alpha version to support flexbox (if I remember correctly) :-) headless chrome is a lot more stable choice imo.
Yeah I think Puppeteer is a very cool project. Unfortunately, it came out literally one or two days after i finished the initial version of pdf-bot. Maybe I will incorporate it soon! :-)