For me it's Fenix E12. I originally disliked the fact it always starts on lowest settings but in the end I like it as it is usually enough and it saves a lot of battery.
Nice, I did the same so I could utilize the clicky of my P1. Was tempted to try it on my P2 body as well but was worried I would fry the QR. A word of warning - the threads on my QR head and P1 body didn't mesh perfectly for the last couple threads towards fully tightened, and as a result my QR head turns a bit less smoothly with it back on the QR body