Which  component should get the best power cable? I

It depends on your components. Start with the component that needs the most "help". For example, a mass market digital player is likely to need the most help.

From the wall to power conditioner or bar. Will impact all other components.

Neal

What if you don't use a power conditioner for your amps?

" What if you don't use a power conditioner for your amps?".

In most cases, power amps sound better plugged directly into the wall. However, a PC can be a nice upgrade, but I wouldn't go any further than that.

Which component should get the best power cable?

Logical component is wall to power distributor/conditioner but it depends if PC is high current or low current.

From my experience, high current is up stream (wall to distributor or amp) and low current is down stream (pre or dac).