Here is my analysis In order of increasing probability:
Swati: Rahul definitely has a strong attraction for her (who would not.. any guy would!!). That is the reason she is still here even after doing minimum interaction and showing least interest to him. But I do not think Rahul would ever establish relation with her family.. unemployed parents dependant on daughter's earning.. that is a burden for him to carry. Also if there was any chance, Sawti has killed it all by saying her physical abuse story. The way she tolerated it and kind of reaction she displayed while describing the story (I loved an insaaan!! come On.. any girl would start with I had affair with an animal ..) clearly states she was/is in deep love with the guy.. no sensible guy would marry Swati after that
Dimpy: Rahul likes her as friend.. no doubt.. anyone would.. she is a great company to be with.. energetic.. friendly.. smiling.. cool headed.. glamorous.. but marriage?? No.. I think a bikini girl.. model is too much as an wife for Mahajan family.. If he can marry Dimpy.. she would not have dumped Monica.. I see no chance here as well
Harpreet: I think Rahul has some kind of motherly affection for her because of her maturity.. He also said that he thinks Harpreet is elder to her.. I do not think they have any chemistry.. Harpreet is too serious for Rahul.. he slept on her lap allright but it was more like a kid sleeping on mother's lap rather than a pair..Though Harpreet has lately started showing signals that she is not suffering from "progeria" (born old).. I guess it is too late.
Mrinmayi: good looking, tall, right age match.. but I think she lacks the class more so because of the way she is badmouthing every one.. she likes none and finds fault with everyone.. I think she is beaten hands down by Nikunj in glamour quotient..
Nikunj: Though displaying the arrogance and bad mouthing of Mrinmayi, I think she is classy and dignified.. the only lady who never did a cheap dance number!! she is educated and good looking (??). Not miles apart in age from Mrinmayi. and yes... tallest also. I just feel like Rahul would land up with Nikunj.. She is someone whom you can produly declare to be your wife to the outer world (whether she would be a good wife or not hardly matters in glamour world...)