My husband works at Whirlpool so I'm biased. The best piece of information I can give you is that appliances are designed to last 5-7 years. If anyone tells you differently, they are full of crap. So, whatever you buy you need to factor in that after about the 5 year mark you will probably start noticing a difference in its ability to clean and even have problems and may once again need to be purchasing a new one. If it lasts longer, hooray for you!!!
I would encourage you to purchase an American made product whenever possible. I would also remind you that Sears contracts with different appliance manufacturers to make their products and not all of them are made by Whirlpool now.
Consumer reports is always an excellent resource. BTW, I love my Whirlpool dishwasher (it's a plastic tub).