If you ask me I would say that best option for Karachi is to vote for PPP in provincial elections (MPAs etc.), yes I know it is an unpopular opinion but in my view it is the right one. Sindh government is not going to go out of the clutches of PPP, by NOT voting PPP the people of Karachi themselves alienate them and make PPP angry so I can understand why PPP ignores Karachi, it is so logical. Vengeance and Revenge are traits shared by people living across indus valley for centuries whether Sindh or Punjab, in this region people historically do take "revenge" in very "innovative ways" just like PPP is doing by ignoring Karachi because for them it is a useless place politically speaking so why should they care about it when the people of karachi will keep hating them and voting other parties like MQM or PTI. Even a fool can also understand, yes people will say about "oh you know this is against morality" but no one gives a damn about "morality" in real politics. PPP government of Sindh wants to spend more money on the areas of Sindh from where they are elected, the day when they will also be elected from Karachi they will start spending on Karachi too.
Disclaimer, I am not endorsing PPP.