This simple LastFor1 Women's Shapewear Seamless Slimming Tummy Control Bodysuit ($15) is the perfect basic that's comfy like a t-shirt. You could even wear it on its own with high-waisted jeans.
"I bought it for one specific event, and it's so comfy I wear it pretty much everyday now," one reviewer said. "I generally wear a bra under it, but it's actually one of the few things I've worn that gives comfortable support without one. Enough for taking the weight off and staying comfy around the house. Smooths out curves without suffocating you."