What are the "best?"
Well.... These Nexus ones are pretty bad ass
Nexus Guages by Autometer (http://hp.autometer.com/products/nexus/index.html) I don't know if they make all of them that you'd need for marine use though..
Personally I like the Autometer Ultra - Lite series alot.. Silver on Silver (that silver is matching to a certain Pewter as well BTW)
Ultra Lite (http://hp.autometer.com/products/ult...solutions.html) Plus if you have a pressure driven speedometer you can order a matching autometer from Rex Marine. (not sure what other types he has that will match, but I know he has these)
Here's some other autometers to take a look at...
[url=http://hp.autometer.com/buyers_guide/product_lines/product_lines.html]Autometer General Products/url]