When I need to resort to a sposie I use Bambo. Have tried Nature Babies, Tushies, Moltex etc and Bambo just seemed nicer and better performing. They are super absorbent, better than Pumpers anyday!
The absorbancy bit is made from starch and is 100% biodegradable so none of the chemically stuff you get in most sposies. And yes, they are nowhere near as good for the environment as cloth washed and dried right, but they are nowhere near as bad as the mainstream brands. Eco disposables are not just about biodegradablity (is that a word?) but also about how they are manufactured, the chemical brightners used, the ingredients etc.
Bambo were ethical consumer's best buy eco-sposie. Cheaper and much better accredited than Sainsbury's. I guess it depends what you are looking for in a nappy, but for me Bambo was a good performer AND about as ethical as I could find for a disposable.
Ethical Consumer's nappy report is still available to view for free at http://www.ethiscore.org/nappies.pdf
and is a really interesting read. I was disapointed that they recently came out and said that people should "ditch the guilt around disposables" (they say that using 1 in 4 nappies as cloth is enough to hit the 10% reduction the government is committed too)
but the article and research is still worth a read.