I've been wearing Gildan for quite a few years. Great quality and reasonable price.
I'd say Hanes or Fruit of the Loom, either would be a good choice.
Dirt cheap but adequate quality and good cotton. Especially the Supima cotton t-shirts.
But if just want t-shirts for wearing around the house then a pack of Kirkland T-shirts from Costco will serve you real well.
Beefy Tees. They're nice & thick & made with exceptional quality!!!