With regards to the Volvos, the old S40 is crap to put it bluntly and not that big either. The new S40/V50 (I have a V50) from 2005+ is a totally different car and really rather good, but still quite compact, more like a Focus estate than a Mondeo in size. Weather you can get one of these for 4K now I'm not sure. But they are also not as cheap to run as you might imagine, fuel costs and general fluids are cheap enough are the 4 pots and go up with the 5 cylinder models as you would expect, but any other parts you might need from Volvo are in my experience at least as expensive as BMW, a bit more sometimes, certainly more than Ford. Other than the fact that the 2005+ S40/V50 have a habit of going through wheel bearings rather fast, they are pretty reliable cars. Petrols are typically as problem free as you would expect and the diesels only suffer the same general common rail diesel issues we see on most other cars of a similar age (which can be damned expensive, DPF, Turbos, Injectors, DMF's, Clutchs)
Other than the fact it's better looking at has a nicer interior (that later of which is somewhat spec dependent though) it really holds no advantages over the Mondeo whatsoever ...costs more too.