Why would you make a third thread on something that isn't terribly important? Oh, and you made it a poll too!
What do you mean? TA Supcom and C&C(+some other) uses Right Click deselect and Left for select/command
Pretty pointless. Everyone uses the first option, only some early C&C games used the left click select/command:right click deselect.
Left click select; Right click command is a virtue of mouse input for RTS game... Even latter Command & Conquer series (from TW to RA3) use it.