If you don't have a tumbling setup already, and have to buy all new gear to get into the game, I would suggest biting the bullet and buy the Stainless media setup. Sure, the barrier to entry is a little higher. It costs more. But the operational costs over the long term are nil. The rotary tumbler should last pretty much forever, and the media should also last forever. The only consumables are lemishine ($4) and dish soap ($4).
Now, if you already have a vibratory tumbler setup, there is really not much reason to upgrade, unless you want to. The captial costs are lower, and the vibratory system is readily available everywhere. But, vibratory tumblers are notorious for burning out quickly. Also, the media will need to be changed and discarded routinely. Also, all the carbon/lead residue from the casings gets loaded into the media, so after a while you get a toxic load of media. Something to consider when you are breathing in walnut dust.
Both systems have pros and cons. Stainless tumbling is wet, and requires drying time. Vibratory tumbling is dry, and ready to use. This is only an issue if you have to tumble, then reload right away. If you only shoot on weekends, and can tumble on a Monday, the wet cases won't be wet on Wednesday. Further, both systems tend to plug flash holes. Stainless seems to plug flash holes less, but they seem harder to unplug compard to dry media. On the whole, it seems a wash between the two. Stainless tumbling is fast, and makes your cases very clean, inside and out. Dry media takes longer, and doesn't clean the cases as well, especially in the nooks and crannies.
Ultrasonic cleaning (a distant form of vibratory cleaning) is still fairly new for reloaders. The small capacity models you will find reasonably priced really aren't up to the task of volume case cleaning. They work great for small quantites of brass, and work great for things like gun parts (trigger groups, bolts, etc.) and other small objects (jewellry). But the less expensive models are troublesome, since they have at best a 50/50 duty cycle, when it comes to running for the length of time required to clean 100 rifle cases. I would consider ultrasonic cleaning if I was a low volume shooter (hunter) and I could also justify the cleaner for working on other small parts.
In my estimation, it comes down to economics, and your current gear setup. If you don't mind the (inital) cost of the stainless tumbling setup, I would go that route, with the only downside being the requirement to dry off the brass before reloading.
