I have been using soft side coolers for many years on the beach and at sporting events here in the valley of the sun. My favorite up to this point has been from Polar Bear Coolers. The only complaint I have ever had with them is that the zippers are not as durable as the rest of the product and they are prone to failure after a few years of regular (about 75 days a year) use.
Yeti has made quite a splash with their big hard sided coolers and they have been well received by high end users in the market. I do not use them (I prefer Canyon Coolers from Flagstaff because I think they are a much better value) but I know many people that do and while they all grumble about the price they do say they are very happy with the performance.
Yeti has a new soft side cooler product called the Hopper and it looks like something I will be very interested in. It is made with heavy duty materials (they call it Dryhide Shell which is supposed to be similar to what is used in whitewater rafts) and big beefy self sealing zippers like you find on high quality dry suits. The Hopper comes in two sizes, 20 and 30 (I assume that refers to Liters but Yeti is notoriously bad at accurately describing the capacity of their coolers), and they are expensive but I am betting that they are very reliable.
If you have a need for a soft side cooler, appreciate high end design/materials and want it to last for a long time then you should take a serious look at the Yeti Hopper. I am going to.