Daypack - Alternatives to Lowepro ComouDay Photo 250?

Thanks for all the responses, I had hoped that out of the hundreds of bags being made at least one would be my ideal bag, however as Harold said I will need to compromise.

I have ordered a Lowepro Compuday Photo 250 which seems the closest fit.

However I may well end up buying a second bag, for use on longer trips or when I need to carry more gear. The National Geographic W5070 looks interesting, if rather ugly, its square shape should give extra capacity for its size - not sure I would want to ware it in the shops though.