Tillage depth- what is best?

Plowing depth for me was whatever the tractor could pull without struggling all the time across the field.

You've asked a very loaded question. Lots to consider there, and you'll get many different opinions. When you say 'soil health', what particular aspects are you considering: Compaction? Maintaining moisture? Keeping organic mater content as high as possible? Reducing spray use for better microbe & micro-nutrient preservation? All important, and unfortunately every tillage method (or lack of) has advantages in one area and disadvantages in another. I don't pretend to be an expert, but here are just a few points to consider:

Don(MI), most every tillage tool has its moment. Kinda like an array of tools in any toolbox.
So in your comment you are more familiar with moldboard plowing? So perhaps that is because it helps your northern colder soils by allowing for quicker warm-up of soil temperatures during spring growing season? Perhaps it also reduces/fractures any upper soil surface compaction(granting your area’s deep winter freezes amend any plow pan compaction created from moldboarding?)? Perhaps it also reduces/controls weed competition versus applying herbicides that may be damaging soil health, etc…, then perhaps it’s a good tool? If what I’ve listed has merit, then your plow seems to be contributing to your soils health. Just observations. No judgements.
Maybe keep using it?

How / what can you do to further help your soil health ~ cover crops.
Easiest? After you fall plow, plant a winter cereal crop (rye,wheat,barley,triticale,etc). Any of these will exhibit root grow throughout the entire winter months, thus feeding soil microbes. Not to mention reducing erosion & capturing abundant soil nutrients & free Tstorm nitrogen from lightning precipitation events.
In the spring, terminate cover crop by choice methods that work for you then plant your regular season crops.
Sorry, I know nothing about disc plows. Point is, use what is familiar to you toward your goal.

If you have rocky ground or areas with tree roots extending out, the disc plow is the cat's whiskers.  Also works good in what we used to call Fredric concrete soil type, where you can plow it till about 10 AM, but then it sets like concrete after the sun has been on it for a coupa hours...

Edited by DiyDave - 20 hours 44 minutes ago at 4:12pm

  The moldboard plow is rare here in western canada. I would say the most used tillage tool is the cultivator or chisel plow .Both terms are used here. 

What I was taught in my area of Iowa, 1965 to 1975.

Only doing corn and beans here. Use a 9 shank Glenco disc chisel w/4" twists after harvest. Almost always 2 passes in spring with 4800 IH field cultivator dragging 5 bar harrow and plant. Some years can get by with one spring pass. This year looks to be one in bean stubble. I really enjoy the snap coupler plows but can cover soooo much more ground with the chisel plow....( and no headlands or dead furrows!)

Thanks for all the comments I do appreciate each of them!

Just posing the question and no I don't actually farm. I have a small couple plots but just enough to get the d14 or wc out and play with them.