The consensus on cars is: there is no consensus on cars. Everyone is shaped slightly differently, and what one large person loves, another large person hates. That said, here are some guidelines on buying a size-friendly, plus size car.
Test drive everything you can lay your hands on. Avoid preconceptions — check out all the cars in your price range. Once you find a car you think you like, try to rent the same make and model for a week or so. You learn much more about a car when you spend some time with it over a day or two.