I don't think we can afford to take risks especially on the CB position. We are already thin there, we need to sign an englishman who knows the league well as wakka mentioned. The prospect of signing someone like Mertesacker is great but it may never work out for us. Cahilll is too expensive so it seems Dann is the clear option.
Some here don't like him, but I think he's a reasonably reliable defender and I would see that position as more priority than a striker just now, given that we have Kuyt.