For a long time one of my favorite pieces of clothing was a basic grey Hanes crewneck sweatshirt-- it's nothing special but it is one of those pieces that I wear all of the time around the house. I would come home and immediately change into it. While I still wear it most days, it has been knocked off of first place by my favorite striped pants from Uniqlo that Claire got me. I ABSOLUTELY love these sweatpants! And they are under $20!!!
If you are looking fora comfortable outfit that you can run to Walgreens in (I feel like I am always in sweatpants at Walgreens), than I highly suggest a Hanes sweatshirt and the lounge wear pants from Uniqlo!!