I use 2 Lyman Turbo tumblers, both with walnut media.
The standard sized Lyman tumbler for my big game brass and the largest Lyman Tumbler for my thousands of .223 brass. Both end up doing an excellent job and the brass from each comes out as shiny and clean as I desire. The longer it's tumbled, the more the effect. Turn it on, go to bed, get up and your work is done.......for now....

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No matter the unit you choose, a well established brand name might be best.