Ya similar skimmer can skim differently due to diff factors for example bio loads as i metioned here... Anyway its hard to judge how good a skimmer is... Like what bro roidan said, as long as can skim, maintain your nitrate at almost undectable lvl, and you like.. its a good skimmer....
Oh ya we also forget some other factors that decide how good a skimmer is, other than looking at skimmate, chamber size or bubble count eventhough this are impt deciding factors... we also have to look at workmanship and the user friendlinest of the skimmer.... A skimmer maybe very very good and powerful but because it is not user friendly that means require very good and acurate tunning to perform many ppl who own this skimmer may not get the skimmer to perform up to its real potential, thus no matter how good the skimmer is, it is not performing due to the poor tunning