You are lucky for you has a oval face. Technically, oval face is the most perfect face that suit for any type and any shapes of eyeglasses and sunglasses. So, both oval sunglasses and round sunglasses you can have a try. In order to get a good look, you shall also consider the your personality and clothes styles when you choose sunglasses. So, just try on and test it out which one is more suitable for you.
You can choose either of them. Oval faces are the most well-balanced face shape, so people with oval faces can wear any type of sunglasses which can go well with oval faces. However, you'd better not wear sunglasses with the same shape as your face. Therefore you'd better choose round sunglasses. Round sunglasses are very popular in recent years due to the retro style. Many people including both men and women prefer wear round sunglasses. Or you can try both on and see which one will look better on you.