(Downingtown, PA, USA)
I think that the best laundry detergent that I've used is Era. I've tried many and none work any better than that one.
I like that it is liquid and not powder, as the powder kind creates dust and in what I've seen, never works as well as a liquid.
Other liquid brands that I've used have either not sufficently cleaned my clothing or have left greasy stain marks on the clothing. Era does neither of these. Also, it is gentle enough to use on my toddler's clothing but tough enough to get the stains out.
One thing that I like about Era is now it comes in a condensed version- that allows you to use half the amount as before to do the same job. Because of this, the bottle is smaller and takes up less room on my laundry shelf, which is small to begin with.
It's also not as heavy to pick up and pour. I also like that it creates less waste this way.
The only problem that I've had with Era is it's blue color- sometimes a tiny blue stain will be left on my clothing and I'll have to wash it again. but it does come out.
I've found that the way to deal with this is to set the water first,stir in the detergent, and then add the clothes. Now that I do this, I can say that Era works perfectly.
Anything that it can't get out I typically can't get out with a stain remover either, so it's that tough.