I don't do much trade in used appliances, but back when I did, it was the fridges you mentioned, the whirlpool/kenmore direct drive washers, and gas dryers.
Dishwashers could not be given away - I suspect because of the install hassle. Electric dryers were not in demand, and did not get much money.
As I recall, anything that needed install was a waste of time: d/w's, cook tops, over range microwaves, etc.
I expect if you focused on basic white goods, you'd do alright.