One important way that shears differ from one another is in the way their handles are arranged. The two most common handle arrangements are offset- and opposing-handle designs. What is the difference and why does this matter?
1) Opposing-handle or level-set design (figure 1). Both handles are the same length. As the stylist cuts with opposing-handle shears, the cutting finger and thumb are in alignment. Since the thumb is being forced back slightly, many stylists find these shears to be less comfortable that offset-handle shears.
2) Semi-Offset or Offset shears (figure 2). The finger blade is slightly longer in distance from the pivot to the back of the finger ring, than is the thumb blade, which is slightly shorter. Offset-handle shears are a much more common style of shear, because many stylists find them to be more comfortable. Why? Because the thumb does not need to move as far while cutting as it would with opposing-handle shears.This reduced distance of travel reduces stress on the thumb tendon, and helps reduce the risk of carpal tunnel syndrome.
So which is best? As with so many things, that depends entirely on which shear YOU find to be most comfortable in your hand while cutting. Being able to recognize the difference between these two styles of shears will help immensely in narrowing down your choice of shears, next time you're buying a new pair of shears.
Figure 1 (Mizutani Retro Shear showing a classic opposing-handle design)
Figure 2: Mizutani "Twig" showing an offset handle design
Figure 3: Image showing difference in handle length, and how this affects whether the shear is level-set or offset.