Wire vs. Vibration vs. Power Cond. is best?

Starting with nothing or the worst quality, which makes the biggest improvement in sound?
* speaker cable and interconnects
* vibration isolation / transfer - speakers and components
* power line conditioning
I don't think there is one 'correct' answer for this question. Is the starter system is something from Snircuit City or Best Poop, a mid-fi collection; what is 'nothing or the worst quality'? I think you need to define a baseline here.
I have taken a friend's cheap rack system and just added better speaker cable with thrilling results. The next step was to modify their systems positioning for better sound. Then isolation / damping, and last a speaker upgrade. At this point, the owner of the system concluded that a better receiver / amp-preamp was needed. Then it was the source units. Then interconnect came into play, and then a power conditioner.
A second friend had a Rotel / KLH based system. Here, interconnect, speaker cable & speaker stands, in that order, made the biggest initial improvements.
In my experience, better wire (generally speaker) will make the biggest difference, in a lower quality system. It has not been the case all the time, but frequently enough, this has been the 'push' that got these people more involved in their music, and prompted them to further upgrade their equipment.
Except for vibration isolation for a turntable, take all the money you might spend on that stuff and upgrade your speakers, electronics, or source for the biggest improvement.
Well I started with power cords, dedicated curcuits and power cords followed by vibration control. This may seem backwards to some but it was a budget issue. I can make more improvements for less money starting where I did.
Does it really matter to an audiophool which affects their music the most? The fact that eacg one does, requires serious attention. These three things are all significant to an audiophool, like myself. I place equal importance on all of them. It's this audio sickness. Remember, your system is as good as it's weakest link. And weakness in any one of these, will affect your sound. How much your music is affected is directly related to your audiophoolishness/mania. I guarentee you'll be happy, beefing up any one of those three. And then you'll be looking to beef up the other two. And then there will be something else. If not, you can always start all over again. Anybody relate to this mania?
happy listening....
I was meaning, not having any vibration control, and power conditioner, and cheap cables. I was just thinking in general with a typical hi-end system, were would money be best spent.
Maybe can't make generalizations but I was thinking maybe a power line conditioner before spending a similar $300-$1,000 in speaker cable /IC's.
Since speakers have a big influence on sound, maybe cones under the speakers would be most important if this would reduce speaker box resonances. I don't know, I'll be trying them all when I can.

Now I understand where you are coming from.

I would say the room treatment would give you the most improvement. For example, a pair of tube traps behind the speakers can usually improve the sound far beyond any component upgrade for the same price. You don’t even need to a/b compare the sound. You will know the improvement as soon as you put the tube traps in. It is that obvious.

The next on my list would be a power regenerator, not power conditioner. I pluged all my front ends to a PP-600. Again, the improvement is obvious, no a/b comparison required.
Some additional thoughts:

Nowadays, almost all high-end speakers come with code feet. And they are cheap. There is no reason not to use them.

In my experiences, unless your equipment is on top of card boxes, vibration control devices give less improvement than power regenerator.

If you have turntable, vibration control is everything.