You might need to invest in some sound proof walls. . . not every meditator may appreciate the sounds of pinball.

Iron Man, BSD, and Fish Tales should do.
I drop the most f-bombs playing BSD

Boy you open a can of worms when you start talking the Zen of Pinball... many older pins can give a real deep meditation, but but only because there is a distinct but acheivable goal besides extra balls, or free games.
I’ll give you two examples, one more modern, the other more traditional.

Twilight zone, Lost in the zone. Getting to this wizard mode and finishing it.

Centaur- achieve 5 ball orbian attack and maintain it as long as possible.

Both of these require deep concentration and great patience. But they differ completely in all other aspects except it being frenetic multiball play. Neither machine is cheap, though, Centaur might fit your list.

You need a Pinball Magic... "Focus your thoughts!", "Concentrate!", ha...

Fish Tales boils my blood. Super f bomby playing that. BSD is a nice flowing machine, once you get all your shots down. Other head down deep thinkers... but inexpensive... High Speed has great flow and not too expensive plus you have to evade the police and get away, Pinbot is always a strong title, but cheaper, multiple goals, reach the sun, solar value, Energy Value, fill the chest to open the visor, lock 2 balls for multiball. great music and light show when all the flashers are working.

On HS and HSII-TGA, Same game updated to DMD and more advanced rules. More to do, but costs more to buy. You need multiple depth machines so you can guide them through their journey deeper with each machine they approach. People starting out can start on simpler machines and graduate to more complex ones, or start with a complex one and slowly try and master it, both paths have appeal, but success will take them a shorter time on HS than on HSII.

But right now I might be tempted to buy a MMr, AFMr, and MBrCE and call it quits. Casual players would find them all three challenging and fun. They are new, and have three very different themes, yet their rules are very similar and deep for casual players. Throw in a Twilight Zone and/or Dialed In and your done. Don’t Judge, but Dredd is not too exspensive and challenging. It has interesting music, but you might not like the Stalone-a-thon call outs.

Depends on what type of sandwiches (deli meats? cheese? Shasta?) you're serving.

Pick up an early solid-state or two so you have something from each period. If you're feeling daring, buy something cheap and worn, and then Hardtop it.