I voted for component cables (which I assume means interconnects or digital cables), but only because the poll choices are a little bit confining. For example, the choices only reference
improvements in sound. I don't think there is much debate (except from certain difficult types) that aftermarket headphone cables
change the sound, but in my case I found that I preferred the stock cable. Hence, the headphone cable did not make the most significant
improvement in sound.
Also, there is a lot more variety and number of component cables than there are headphone cables. Thus, I think it would be relatively easier for me to find a component cable that, for whatever reason, makes a more significant change in the sound -- good or bad -- than a headphone cable. For example, I really did not like the sound a certain silver interconnect in my system. But again, the issue was not one of improvement. Generally, though, I would say that all headphone cables change the sound, while the sound changes from many interconnects might be relatively harder to discern.
Also, the choices do not include power cables. And the changes made in my system from changing out the power cables were very close in terms of magnitude to the changing of my interconnects.
As to whether the changes -- good or bad -- are significant, that's always in the eye (or ear, rather) of the listener. One can say 5 to 10% is not signficant. But if you're system sounds really great, and you change a cable and improve it by 10%, it can make a whole world of difference to your listening experience.
Actually, it's pointless to talk about a 5 or 10% improvement anyway. Nobody has ever identified a standard of measurement that would allow each of us to determine what a 5 or 10% improvement sounds like.
Finally, a plea for keeping this discussion friendly, informational, and devoid of the usual attacks on people who believe they hear differences in cables ("it's just like believing in Bigfoot,etc.") Please.