WHat is the right way to sidechain?

I have tried 3 different apporaches to sidechaining. I have made 2 layered piano sounds in 3 different channels. Fx, Group and also 2 seperate insertchannels. When sidechaining them I come to 3 different outcomes in sound using the same parimeter in compressor. I felt that the seperate insert channels sounds the best and what I am always used to do. What do you girls/guys recommend?

Right is what sounds the way you want it.