I'm going to use eco disposables. The environmental/financial cost equation for reusable versus disposable is a lot more complex than it looks, and the info councils give out is very skewed - for political reasons.
The financial costs look much cheaper for reuaables, but are not, it works out around the same - once you take into account the cost of electric,water and cleaning products. Most studies use unrealistic data to come up with the costings - ie, that you only ever run a full washing machine, at 30 deg, never a hot wash, and never tumble dry or use a heater to help dry the nappies. Even under these "ideal" conditions, which NO ONE is going to be able to match up to in real life, the total cost are only fractionally cheaper than disposibles.
The picture is the same for the environmental impact - including landfill costs for disposables, the chemical/water treatment costs for reusables, the two come out roughly the same in terms of impact.
If you use a nappy laundry service, you will increase the impact of using reusable nappies by a big chunk - the extra transport costs/carbon footprint, and they will be washed hot and tumble dried, every time!
As around 25% of the total energy used to make a disposable nappy is used to bleach the wood-pulp/cover etc to make it white, ANY type of eco unbleached disposable nappy wins hands down on total environmental impact over either normal disposibles or reusables.