A round neck like this works well under sweaters and hoodies alike.
Gildan Light Pink G200 Ultra Cotton T-Shirt G2000 Size S ~ 3XL Rosa Z7 camisa
This t-shirt has a round neck that feels light and barely there.
Gildan G200 Safety Orange Ultra Cotton T Shirt G2000 Sizes S ~ 5XL s/s Z7 naran
A nice touch is the gentle curve of the round neck across your chest.
Gildan G200 Heliconia Small Ultra Cotton T-shirt G2000 Pink camiseta Rosa
This shirt has a comfortable round neck that sits just right without riding up.
Gildan G200 Irish Green Ultra Cotton T Shirt G2000 Sizes S ~ 5XL Verde Ireland
The round neckline here is perfect for wearing under a blazer or jacket.