It depends on what your budget is. The flats in clifton / defence are safe in Karachi but cost a lot of money (a 3 bed flat in clifton may cost you $200k plus). Don't buy in the new areas around outskirts of Karachi even though there are many good deals around these days. Do not rent out your flat as the tenants may stop paying (happens all over the world!). I would suggest Creek Vistas (Defence) as you can pick up a 3 bed for about 1 crore (I think).