That's a very personal decision. I would say that you should buy only coins that will bring you joy when you look at them. But I would say that the price should also be fair, so I would take that into consideration. Personally, I like the looks of the 1740 1R, but I would want to see higher resolution photos. 1757 is scarcer of the lot. 1831 has potential to be in an attractive grade, but again it's hard to tell from these photos.