If you’re having a hard time finding a good comic reader for your Mac, Jomic is a lightweight, open source, and snappy comic reader available for both OS X and Windows.
It supports all major image formats as well as comic container files (CBZ, CBR, etc.), full screen playback with side-by-side page presentation, and keyboard shortcuts.
If you’re looking for a Linux-based reader, make sure to check out previously reviewed Comix. Jomic is open-source, Mac and Windows only.