When it comes to selecting a ski, I believe that the differences between skis / ski manufacturers are much more easily identified the higher end you go. I think that most would agree that when it comes to beginner / beginner-intermediate skis that a lot of the manufacturers produce similar products. Anyway,
Here's my ski selection checklist so to speak:
1- Ski's intended usage.
I know the way I like to ski, and wouldn't choose a mogul ski or superfats if I don't ski moguls or powder, etc.. Also, based on my ability, I wouldn't choose a ski that was too low end, or too high end for how I ski, and how I intend to use it.
2- Ski Dimensions
I know that I prefer ski's between 168 and 178, and depending on the turn radius of the ski, and it's T/W/T dimensions I know if the ski would suit me.
I think that manufacturer's seem to achieve a consitent "feel" throughout their model lines. This is because throughout a manufacturers model lineup, they use the same constuction technology for a said group of their products.
For example; I may consider Brand X to be much more "damp" than most Brand Y skis, and depending on the intended use, I might be looking for something light and snappy, or something that cuts through crud like butter.
4- Materials of Construction
If I'm not buying race skis, I tend to try and select skis that are influenced with materials and construction techniques from the particular manufacturers racing line. I feel that this way I know that I'm getting the best quality materials and technology the manufacturer has developed. For example, If a ski uses the same sintered base found on the race skis, to me that's an important selling feature.
5- Binding Choices / Plates / Built in Gimicks
I'm not a huge fan of plates and gimicks that limit a skier's ability to choose what binding system / gimick they want on their skis. It might go as far as to eliminate a certain ski from my list if I have a particular dislike for that companies bindings. But it could also entice me to consider a ski more seriously if the binding system, etc is one that I know and trust.
That pretty much sums up what I go through in my head when I'm looking for new skis. By using those listed characteristics, and my past experience with different skis, and by demoing new skis I have yet to try, I usually find a ski that makes me grin!