Microfibre inserts and nappies are bulkier, but dry really quickly. Bamboo and hemp inserts and nappies are very slim fitting, as they are the most absorbent fabrics, but are slow drying. Hemp goes hard with washing, especially in hard water. Cotton is a medium absorbency, medium time for drying fabric, but not very environmentally friendly in it's production.
You can get either shaped nappies or inserts for pocket nappies in all these fibres. The biggest consideration you need to make is what drying facilities you have - drying can be a problem in winter, if you have neither a very warm place to hang them u, or a tumble dryer to use in emergencies!