If you have a choice which one will you choose? Will you dump your power conditoner over your dedicated line? Or will you have both?
While I am NOT an expert, I think in general we need to consider these elements regarding POWER;
1) Power/Current Availability
2) Power/Current Stability
3) Power Filtering or Reduction of Noise Producing artifacts or elements
A Dedicated Line will likely help 1 and 2, but not totally
A Power Conditioner, depending on the method or methods of conditioning/treatment or storage can benefit all three.
In general I find Power Conditioners to fit into various types of "conditioning".
1) Filtration to "clean" your power
2) Balanced Types to cancel noise
3) Current Stabilizers (through various storage means)
4) Voltage Spike Protections
5) Magic Beads (claims of some type of non-disclosed proprietary benefits)
The degree to which each, or any of these will help your end Sonic Product will depend on the condition of your current as it comes to you. This is no doubt why many rave at the "incredible" improvement,

while others find little value at all.

If you are able to figure out what might be beneficial to "your" particular system and power supply, then the selection of solutions might be easier.