This has been a quite debate with my friends. I grew up playing Halo in Xbox & always use Right Analog Stick click to zoom in the reticle. This has been my most preferred way to play FPS, especially Halo. Even in Halo 5 I changed the controller scheme from default to Recon as I already got used to clicking analog stick to zoom. However, I do played other games that use Left trigger to zoom in, like GTA IV & a few. Those few games does not offer button mapping in-game but I got used to the layout fairly quickly. Left trigger zoom seems to be the norm of the modern console FPS layout nowadays. Most of my friend now prefer to use it rather than the analog click. Which one do you guys prefer?