Best media for dry tumbling?

[handcannon]

So I've recently saved up enough pennies to get a dry tumbler. I've already caught on that lizard bedding made from walnut is the same as the walnut media. I also see that corn cob media's out there. When do you use walnut and when corn cob? The walnut seems to be doing a good job, especially when I occasionally put in a couple squirts of ammonia free Wright's Silver Cleaner and Polish (which also says it can be used on brass). Thanks for the advice.

Corn cob for me hands down.... with a little cap full of liquid NuFinish car wax.... Northern Tool you can get a 50# sack for $40....