I use washing powder, in the biggest box that I can find on offer. It lasts us ages, and I use an old coffee scoop to measure the dosage, usually 1good scoop per wash. I have tried liquids before, but found that they left a decidedly " sour" smell in the machine. I do use softener, diluted, but find that it leaves a deposit around the dispenser, that can be hard to clean off.
When you could get it, I found that good old fashioned hard Sunlight soap bars were excellent at cleaning stains. Now the stuff you buy, on line, is pretty useless, and is definitely not the same. So much for progress. When I asked Sunlight, why they didn't make and market the original product, they told me, there was no demand!