I have the 2 liter Hornady sonic cleaner. I don't use the solution that Hornady makes because I don't care for the price and I think homemade concoctions can work better and for less.
I currently use dawn dish soap and Lemishine. This appears to be a good solution.
I also use the heat function.
What I have found with the 2 liter Hornady cleaner is that the brass has to be as close to the center of the unit to be effectively cleaned. Also, you can't just pour brass into the cleaner and expect it to be clean in 5 mins. I stand the cases up in the plastic bin and lower it into the cleaner and that seems to be most effective.
.45 Colt cases are nice and easy to do this without them falling everywhere, .32 S&W Long/H&R Mag is a total PITA. Can be done if you're patient.
Gun parts come out very nice, other metal stuff gets cleaned well too.
I wouldn't spend the money on the large ultrasonic cleaners, I just don't trust them to do the job on brass. If you want to clean AR uppers, just do it by hand. If you want to clean a lot of brass, I believe the rotary tumblers with stainless pins is the best way to do it. I don't shoot or reload enough to justify getting a rotary tumbler, but it's on my list of equipment to get when I start shooting more.
I believe the smaller ultrasonics are great to have for small batches of brass and general cleaning, but they have issues making the brass look brand new. I'm sure the brass does get to the "clean enough" for reloading after a good 10 minute cycle, but I like knowing the brass is clean by looking almost new. The machine can do it if you give it 30 minutes, rearrange the brass and take out the clean cases, keep the water hot, and not overload the container.
That may sound like too much work for some and I understand.
If you want to know more, let me know and I'll let you know what I know so far.