I have three: Dillon CV-2001 (large model), Thumlers Model B (rotary type), and a Berry's small vibratory tumbler.
As far as what is best, it depends on what you want. The Thumlers shines brass like no other. I seriously had doubts about its' abilities, but it blows away the vibratory models. If all you need is functionally clean brass, get a Dillon or other comparable vibratory one. If you're looking for bling, get a rotary type. Keep in mind, the rotary ones take a bit longer as they tumble a lot slower. The Dillon is on no longer than two hours at a time. I run the Thumlers for a few days at a time. The Thumler is also realllllly quiet.
Ed