As expected, there are as many different opinions as there are people. There are those that view the receptacle as the last piece of the electrical supply to your system. If you consider that alternating current electricity does not flow in the way that water flows through a pipe but, more or less just moves back and forth on the wire (I know this is simplistic and I am not an expert on electricity) then the receptacle and/or power cord perhaps should be considered the first component of the power supply to the system (the cord is the first six feet of the power wiring that your system sees not the last six feet of the circuit and it is a circuit not a dead end). Therefore, in this view, the quality and sound characteristics of the receptacle are important enough to be willing to spend money on, at least to those who figure that every single thing matters in the system and can hear the differences.
Now, to narrow the choices you may want to consider what metal is used for the conductor. Is it basic brass or the higher level of brass known as phosphor bronze or pure copper? Each type has its own sound.
Next, do you want any kind of plating and if so what kind? Maybe, you want it to be un-plated? Again, each type of plating has its own sound.
My personal preference is for un-plated pure copper receptacles. I have used the Cruze First Maestro which is some form of brass alloy. To my ear, they are more neutral than plated receptacles but, bare copper sounds even more neutral to me. However, there are variations in the sound of bare copper from one brand to next also.
The Oyaide R-1 has been mentioned which has similar plating to their 004 cord ends.. Oyaide also has the R-0 which is un-plated copper. I have two of the R-0 in my main system. Interestingly, I prefer the Maestro in my second system.
There are many choices out there. You need to try several to figure out what combination of materials fits your preferences and works well with your system just as you have to do with power cords.
Then there is Cryo treatment, a whole 'nother subject.