I own the K10.2 and RCF NX910A both, I prefer using the NX910A as PA because it sounds warmer and has more definition. Also the RCF NX910A is from wood. But both deliver really clear sound. But I’m enjoying the sound of the RCF NX910A more, you can distinct all of the tracks/instruments more in the music.
I prefer using the QSC K10.2 as a monitor since it has less low/mids, which is in my opinion great for monitor applications. Also because it has more I/O and DSP options I prefer to use this as a monitor. I really like to use the DSP monitor preset, it helps to avoid feedback. Also the QSC K10.2 is more solidly build, since it made of plastic. It can handle a bump easily, I already damaged the grill of the RCF NX910A. I don’t see that happen with the QSC K10.2.
QSC K10.2 is actively cooled, so you can hear the fan if you use it in a small room and you’re not running sound. So not really annoying, but something that you can keep in mind if you want to use it in a practice room/home studio application.
So both are great speakers, If you prefer more I/O options and a more solidly build speaker, QSC K10.2 is a great option. If you like the warm wood sound, go for the RCF NX910A.
But of course, I would recommend listening to both first and then choose!