I would highly recommend both, but if only one, I'd get the tumbler. You can always clean things by hand.

if you buy new starposts there wont be much left on taxi that you can clean ultrasonically so buy the tumbler.

Tumbler will be of more value as a first purchase.

I have no idea why so much talk about UCs. I have one and not a cheap one and I do not think it is helpful or special at all. I do not have a tumbler but can see it being way more helpful.
Polishing all the hardware. So my vote would be (tumbler or vibrator). Oh now there is a third option!

tumbler cleans way more and better. My UC doesn't get used much and when it does, I don't think it does all that great of a job.

UCs are overhyped, unnecessary luxuries IMO. My experience with one has been disastrous. Doesn't seem to actually clean much of anything.

Get a tumbler. I wish I had. Maybe the dust stuff will work better!

They are two different things. It is not an either/or. Buy both.

Two different beasts so it depends on what you need. the Ultrasonic is a cleaner, the tumbler buffs/polishes. If you have the time an overnight soak in Simple Green will do the same job as a UC, just takes longer. Nothing really comes close to a tumbler for little bits.

Which tumbler or SC do you prefer?

I use the large Dillon Precision tumbler. Have had it for 20 years or so and still going strong. If it fails, they have a lifetime no BS warranty.

Other than that I'd get as big a bowl as you can. Otherwise there will be that piece that just doesn't quite fit...

You can buy media from Grainger in 40 or 50lb bags fore much less than the gun related packages...

I love my tumbler, but the ultrasonic was a waste of money. I can do the same thing with some cleaner and a toothbrush, and with the ultrasonic, I have to do that anyway to make up for the crappy job it does.

I use my ultrasonic cleaner for everything... I purcased a really nice, heated large one. I put ramps, plastics, posts, pop bumper parts, flipper assemblys, habitrails, coils -anything that will fit. I dont use anything speical- just water and a little dish soap. I even put painted plastics in it- (I only put those in for a minute.) I dont have a tumbler, and I dont want to wait hours.
I really don't polish a lot of metal- there isn't much to polish on the top side- I re-grain ball guides, and buy new screws/nuts that show.
I could give a rats ass if the underside of the play-field parts are super shiny- I just want it clean so it stays working.
Your choice may need to be based on your restore/shop expectations.
If your striving for "HEP" type of machines, a tumbler may be what you get first. If you want to clean and play it, maybe a ultrasonic. Either way -don't go cheap!
Just noticed this thread is a year old... guy prolly made his decision-
T2play -I bought a Kendal 21 liter