All of them are cute, but really depends on the day and weather.
Fall and winter are easily a sweater, no questions asked.
Spring is generally a t-shirt. Mainly because it can still get a little chilly some days. Usually it's freezing in the morning, but 70 degrees by the afternoon. A t-shirt covers up just enough but also leaves just enough exposed to stay cool.
Summer it's usually a crop-top, but since I work full time at a pool, I just wear a bikini. But if I don't feel good for whatever reason, t-shirt.
As you can see, I have a set of specific rules for my outfits 
