Incorrect icon weight on the right.

Avoid cramming the 128×128 canvas with full-size square graphic. It’ll make your dock feel heavier and not balanced.

What you’ll want to do:

Unbold the icon by resizing it to be slightly smaller. My recommendation is -11 pixel width/height.

May vary depending on graphic weight.

The result:

Balanced dock after the resize.

Better comparison example:

Ahh, roomy dock.

Correct weight is what you’ll need to make icon sit comfortably in the dock. Same tip can be applied to circle or diagonal shapes.

Note: In some cases, full 128×128 may be necessary. This is mostly good for icons with heavy transparency (ie: large shadow area, transparency objects, etc.)