MDK

MDK uses FL Studio in tutorials, as can be seen in this video.

FL was also MDK's first DAW, as mentioned in this August 26, 2015 interview with Image-Line:

How did you start using FL Studio & what does it mean to your productions?

I downloaded the FL Studio (version 7) demo when I was 14, and was instantly hooked (though I’ll admit I came very close to uninstalling it because I didn’t know you could change from “pattern” to “song” mode #noob). After a few days of messing around with the demo I realized that I was seriously addicted. Hell, “addicted” is an understatement. It consumed all of my free time and I realized that it was what I wanted to spend the rest of my life doing. I managed to convince my mom to buy the full version of FL for my 15th birthday (which wasn’t easy – that was her first online purchase ever), and the rest is history!

I’ve tried most other DAWs at this point, but none of them have ever felt as intuitive as FL. It’s the perfect balance of a sleek, user-friendly program, and a truly badass piece of audio software.