The answer for typical French/American (broadly) stews is meat before onions to get a good sear, and a good fond, to base your stock on. Doing this properly (including not crowding) will always give better results. You should really remove it before the onions also, but that’s an extra step.

I thing with a lot of things like this the better technique is known, but often more work and the lesser technique isn’t a disaster so people use them. Also doing all the steps “right” will give you a better result , but missing sometimes even one will leave you about where you would have been not bothering.

And some of these things compound. In your example, there is literally no way to really recover from an improper sear in a beef stew that calls for it; it's probably the number one cause of mediocre versions of these.

(I'm trying to be careful here because there are equally valid was of doing this - an American stew using Moroccan techniques, or vice versa probably won't work as well)

> My suspicion is that most of the contradictory advice is for things that don't matter that much.

I agree, I think game changing advice would get noticed and passed around quickly, and for things that make no difference or minor difference you'll see lots of people sharing contradictory anecdotes.

Also holds true for many other things, e.g. parenting.