RebelLabs started annual Geek Choice Awards, and Jenkins was one of the 10 winners. See the page they talk about Jenkins.
My favorite part is, to quote, "Jenkins has an almost laughably dominant position in the CI server segment", and "With 70% of the CI market on lockdown and showing an increasing rate of plugin development, Jenkins is undoubtably the most popular way to go with CI servers."
If you want to read more about it and other 9 technologies that won, they have produced a beautifully formatted PDF for you to read.