No scientific proof at all but it feels like washing powder does a much better job at removing stains than washing liquid.
It also seems more and more difficult to find washing powder in store as manufacturers are moving to liquid and even more a rip off - pods. Don’t get me started on these money spinners.
What is your experience and what works best?
It all depends on the quality of the product you buy. I tested good brands powder and liquid and they’re both good. Liquids are easier to refill in the machine. Powders are a bit better in value.