If you want an allround solution then a set of Eibach 35mm lowering springs will be absolutely fine and won't cost the earth.

If, on the other hand, you want the bestest of the best kit because you're going racing then can I suggest something like the Bilstein PSS9 kit (if they are available anymore) which is a phenominal bit of kit.

My Focus has Koni adjustables/coilovers because I did track days/racing in mine. My missus' 1.6 Focus is lowered on a set of Eibachs and they have improved the handling immensly without affecting the overall ride quality (on shitty British roads) a huge amount.