Ally is cheaper, easier to read, but only 7 characters.

Acrylic is more expensive, harder to read, and goes to 9

The acrylic seems to go duller a lot quicker too, where as the aluminium plates stay shiny all the time as long as you keep them clean.

If you can handle the 7 character limit, I'd be going the aluminium plates.

As above, full size on rear and slim on front ftw.