saddar student biryani used to be good...taste is long gone
for biryani you can try following
ALLAHwala at society office main
Food Centre At Main Burns Road
Jamil Foods At Dhoraji
If You Are Fond Of Nalli Biryani( I Dont Like It) Then Ghousia At Main Hussainabad Food Street
There are many more at almost every point of Karachi...