Twin Strollers and Carrycots - Which to Choose?

We are looking to invest in a stroller that will be our main mode of kid transportation (as we don't have a car), and therefore don't need something car seat adaptable for everyday use. I've been looking at twin strollers with carrycots and am wondering if anyone has any insight as to whether a double carrycot or two single carrycots would be a better idea. We like the idea of having them together in the double, but can see potential advantages to having them separate as well, so not having any experience with twins we don't know how to decide. Any thoughts would be most appreciated!