I have heard that the Saab 95 is quite mean for boot space. Cars for your requirements that immediately spring to mind consist of the obvious Volvos, but a former colleague of mine who was a keen fisherman replaced his ageing Passat with a Chevrolet Lacetti Estate. He only kept it a year, changing it not for lack of bootspace (it was ideal there) but it got through petrol like George Best got through Champaign.
Mondeo looks good. However if you lean forther towards the GM stable then the Astra estate is far more practical than the Insignia.