When I first started, I used 9s. A couple of years later, when I was 16, I went to 10s on my Les Paul, in order to stop breaking strings, since I was playing in a band, and pretty heavy handed, I guess.
About 8 years ago, I bought an EVH Wolfgang guitar that I would pick up in the music store while my son was having his guitar lesson for about 1/2 a year, and was loving the Floyd Rose, so I bought it. It had 9s on it. I promptly re-strung it with 10s, and I hated how it played!
I switched it back to 9s, and all was well. Eventually, I did the same with my strats and Les Paul, and now I play 9s, and 40 years has since gone by since I used to break strings, and I am still not breaking them, so I have probably developed an lighter touch, so I'm perfectly happy with the 9s in my 3-piece (instrumentally) band.