You are considering cars which have different price ranges. Be more specific in your price range so that members can give their advise/opinion accurately. However some points from my side,
As far as Mira is concerned, i personally stay away from JDM due to very high current prices and spare parts price and ready availability of spare parts. Although quality is better but i have seen too many jdms get hit on underside by karachi speed breakers.. (breaks my heart too).
for alto: , A work place colleague sold his new shape alto after a year saying that its too slow with 4 to 5 adults. Looking for bigger car. He sold it more than he got it for though. Otherwise its ok ideally for 2 adults and 2 children.
Cultus would be a decent (not excellent) overall package. However i have driven it with 4 adults and you can feel the lag when it starts from stop. its quality of body metal is just so so.
BUT one major factor is that what the new prices are now. If it touches 20 laks then i will humble suggest to stretch your budget quickly go for Yaris GLi at 24 laks as it will get delivered in 1 month. At least its a proper car with excellent AC, pick and capacity.
Best of luck.