A round neck t-shirt typically has a circular neckline that sits close to the base of the neck. It's a classic style that suits most body types and can be found in various fabrics, including polyester. When it comes to the best polyester t-shirts, look for ones that are made from high-quality polyester blends that offer breathability, moisture-wicking properties, and durability. Brands like Nike, Adidas, and Under Armour are known for their quality polyester t-shirts that are great for sports or casual wear.