Chain or cable should provide a smooth rowing motion. As one foot pad moves forward, the other automatically moves backward. Usually less costly. Platform should be stable, not shaky. Choose a skier that can change resistance without stopping exercise.
Some models offer adjustable inclines.
Skiers can consume a lot of space unless you choose one that folds up. The more money you spend, the better the machine is in terms of durability and comprehensiveness. Keep in mind that these machines take up lots of space. For the best muscular-fitness workout, choose a machine that uses weight plates for resistance rather than bands, shock absorbers or centrifugal brakes. Make sure it is easy to do different exercises without a lot of machine adjustments.