I believe in conscientious maintenance of the skimmer cup and neck, if those area are dirty, how best a skimmer can be will also underperform.......
Some items worth considering when comparing skimmers -
-Ease of maintenance
-Ability to reduce bubble escaping
-Skimmer ease of tunability
-Required pump to drive skimmer -ie. heat, power consumption
-Workmanship
-Bubble size
-Cost
Pretty hard to compare.....individual preference....