When our old agitator Kenmore died, DH got a good deal on an impeller from a friend of his. Can't remember the name, but I hated that from the very start. I would take clothes out and not only were they not clean, they would have soap residue and even dry spots! I started putting less and less clothes in hoping for a better result and nothing worked. Family of 5, three teens. My basement was filled with clothes waiting to be washed. I complained every time I had to wash another load, So with the number of loads, that was a lot! (no wonder the guy gave him a good deal, it was worthless)
I researched and found the best rated was a Speed Queen agitator and as mentioned above, a stupid one. Cost around a $1000 a few years ago. When we were looking and the guy gave us the price, DH wasn't supper happy, but I was adamant.
It is the absolute best washing machine I have ever had, well worth every penny. I think the year we bought it, they changed something in the design, and not for the better. So really lucked out there. Put the old junk of an impeller in his mom's rental unit for the tenant. They were happy not to have to go to the laundry mat, but I often wondered if they still felt that way after actually using it.