interconnects vs speaker cables vs power cords - which make the biggest difference?

Hi falconquest,

I also agree that power cords make the most sonic difference, with or without a power conditioner. For the record, I use a SR Powercell 10UEF/FEQ and the power cord between it and the wall makes the most difference IME. Digital sources would be next.

Dave

My prescription has been IC, SC, and then PC.  YRMV. 

if you are tempted to spend more than $200 on all cables combined (for a normal sized home) then just hit yourself in the head with a hammer

Are you applying that to budget systems or any system?

My own experience and I believe the audio mags support power cord first then interconnect, then speaker cable.

As others have mentioned, it's system dependent.
With that said I'm going to answer your specific question and not get into other areas that you didn't ask about but others alluded to.
Power cords, interconnects and speaker cables in my opinion carry a signal or current of some type and can be used to tune your system (sound wise) to your liking. I find all three equally important.
If pressed to rank them in order, I'd agree with others that said:
1) Power cords
2) Interconnects
3) Speaker cables