For me, I prefer a square Smartwatch. But, as stated earlier, it's just for aesthetics, I like square, some like circle.
That said, I love the S2. I came from the Gear 2 Neo (square), and the S2 is hands down a better watch. I like the circle aspect of it because it goes beyond aesthetics, where the bezel actually has a useful function and the circle shape makes sense for the user interface.