My favorites, as far as aesthetics go, are the Swimaster capillary gauges that were produced in the 1970's. While they are not real accurate, particularly in deeper water, they are about as simple as it can get.
Here is a link to a photograph of the Swimaster DC250. It has a tapered inner barrel, which is designed to keep the depths more evenly spread out.

So, what gauges are among your favorites?
Greg
Greg I hooked you up on Photobucket.............Bryan