I learned last year that how your skis are constructed makes a difference in how they ski and how long they will last. Here are 3 basic ways that skis are made.
The first way is a cap ski. A cap ski’s top curves around from one edge over the top skin to the other edge. Cap skis can be found in inexpensive and fairly expensive skis. Cap construction is popular with ski manufacturers because it is simpler than the other ski construction methods. Some cap skis are injected with liquid foam. Foam cores, whether shaped or injected tend to crack everytime the ski is flexed which makes the core break down over time.
A torsion box ski usually uses a wood core surrounded by fiberglass. K2 makes a lot of good torsion box skis. Torsion box ski construction provides tortional rigidity so that the ski resists twisting which adds to edge grip and aids in turn initiation.
A laminate or sandwich ski has superior edge grip, and is prized by ski racers. The way the sidewall is constructed makes it transfer input to your edges better than other construction methods.
My recommendation is to avoid caps skis because they tend to be less durable, and have less edge grip.