it is all dependent upon your taste; they both do a good job. Tumbler is "easier" in terms of time consumption; I just set mine before I leave for work and let it run on a timer. Ultrasonic can't do as big of a batch at one time and requires a little more hands on. Ultrasonics can also do more than just clean brass; small parts and bolts can be cleaned in a few minutes.
Start at the very beginning: You need to wipe off dirt/sand/grime from the case exterior so you don't damage the sizing die or put scratches down your case.
Any cleaning beyond that is being done for your own personal desire for clean/shiny or to save time from wiping off each case.
Thus, either one is far more than needed.
I prefer to deprime my brass and tumble for 30 minutes in 20/40 corn. Ultrasonic can get the brass cleaner (clean interior and primer pocket), and the black residue being removed has no effect on function or accuracy, but you then have to rinse the cases in water and dry them.
I prefer tumbling over the ultrasonic for the simple fact that I don't like having to wait for my brass to dry. Utrasonic does a great job cleaning, I just prefer to tumble with a little polish in the media. I get great results, and I like the sound of the brass rolling around.
I have both, Tumble & Ultrasonic. 75% of the time I use the Tumbler.I find it less of a hassle.I soak the cases 1st for 30mins in warm water & Limescale Remover,then wash them in plain hot water after rinsing well in warm soapy water.by this time they have a very weak pink tinge in colour.I then put them in the tumbler media for about 1& 1/2 hrs and they come out looking brilliant.I then clean out thr primer pockets plus any corn cob left inside.put them away till the next day to thoroughly dry.If you dry them 1st before the tumble I find doesn`t shine the cases as much as putting them in wet; but the joice is yours as to how quickly you need to start loading.Must point out I only reload handgun cartridges,so am not quoting the above for rifle rds as I have no experiance in these.