Ofcourse shaan with khanak.Natasha no ways...
From the beginning natasha did nothing to make him a better person.Nododubt she brought him out of the trouble and all that.,since they were together.Remeber the first episode where shaan hits aa polic jeep and lands in jail.,natasha bails him out.
But she neither advises him on his behaviour in a proper way( she sor of tells him but not prperly in a stern manner) nor does anything to correct that.She does things for him and spoils him.Plus the sort of company she gives is highly boring.There is no fun at all.
Where as khanak has always told him of his flwas.Even at dhulwadi rember she told that he was a selfish person daringly.After he bacame her husband she is truly interested to make him a better person even though he did not like him initally.
But now she knows he isa nice person and once he is shown a proper way is bound be a fine human being.So she is helping him in that aspect.,without interfering much. And she gives good company to him.,as both shaan and khank are sort of funloving persons.
Above all shaan looks good with khanak as they both look young and cute.I am sorry to say natasha looks very much old to shaan.(in my eyes)
Thoug khanak and natasha both are good khanak outshiines natasha with her selfless heart,helpful nature to all,capacity to face troubles without much agitation,and her unconditional affection for shaan.
So khanak all the way.