2D / Static Eyes

These eyes are made with polystyrene plastic sheeting for the sclera, mesh for the iris/pupil area, and stiff felt for the eye rim/eyelashes. They are always looking in a set direction and the eyes are flat and glued onto the outside of the head. Appear brighter, no shadows are cast in/on these eyes.

3D / Follow-Me Eyes

The most popular style currently, because of the fun optical illusion that makes the eyes look like they are always looking at you/the camera! I 3D model and print the 'eye cups' from PLA which make up the sclera and a short wall surrounding the eye which gives the 3D effect. Note that because the eyes are sunken in to produce the effect, they are more prone to lighting casting shadows inside the eye. I model the eyes with a slight slope inside to avoid as many harsh shadows as I can.

3D / Follow-Me Eyes, All Mesh variant

These are very similar to the regular following eyes, but the sclera is also mesh, so you have even wider side vision because there is no plastic in the sclera. Note that since the plastic is only around the edge, there is no gradual slope from the wall to the mesh, meaning there is a more harsh angle at the corners which catches more shadows and is less seamless. In my opinion the harsh corners detract a little from the following effect, making it less pronounced!
If you are getting glasses room/padding in your head, this eye style is one way to make up for the slight loss of vision due to being further away from the eye holes. It is not necessary to choose this eye style to still have a good suiting experience, though.