A production/or homemade tumbler with Stainless Steel is the way to go.
I started off with a vibratory type when I was in University and used corn cob for years. It would clean the outside of the cases and I tried various concoctions to get them clean and shinny. After using it for 20 years and having it running at least 48 hours a week it finally gave up the ghost.
So I bought another one and continued on. I hated cleaning the media out of the primer pockets and having it take so long to clean the brass.
I then jumped on the bandwagon with the ultrasonic. It works OK but you have to constantly babysit it. Most only run for 8 minutes and then you have to reset it again. It will get the brass clean inside and out but not shinny. You can go thru various stages of different concoctions to get the brass clean and shinny but with the amount of brass I have it would take forever to get done.
I recently built my own rotary tumbler and use stainless steel pins and it is fantastic and I never have to buy a thing again other than soap. I have a large quantity of brass to do so that is why I went with making my own. I can have 500 30-06 brass clean at once, takes 3 hours on the tumbler, 15 minutes to separate the pins from the brass and spread the brass on a towel to dry over night. No baby sitting involved. I bought a cheap 10 buck timer and turn it on before going to work and it turns off 3 hours later.
Commercial tumbler will do smaller batches but still as effective at cleaning the brass. I took some WW2 range brass that was corroded so bad I thought they were throw aways but 3 hours in the tumbler and they look new.
Here are some before pictures of the range pickups. Really nasty, scaled on dirt and green rust (not sure what it is), and I thought were basically just throw aways.
Look at how nasty the insides are.
Now 3 hours in the tumbler later.
Now look at the insides. Much cleaner. They are the same brass as before and you can see that they are by the mouth of the brass was squished by people walking on them in the dirt.
This stuff really works and I wish I had made my own tumbler earlier. Hope this dispels once and for all people not believing that it works. As they say Pictures are worth a thousand words.