i think the reason why Abhi is liked is cos, he hasnt done too much damage to the AR relationship.... plus the way the character of Abhimanyu has been shaped out, it shows he is totally a work oriented man.... he has shown no obvious interest in Riddhima so far and has treated her no different from the rest... even the other day, when Riddhima accuses him he stands his dignity and walks away... obviously its an endearing thought... and another thing that many ppl may deny, but cant ignore is the fact that this forum has a plethora of girls, the chances of them finding a guy hot are high, as opposed to a gal....lol... i may be wrong there though...
Niki on the otherhand is more of a glamor addition to the show and, she has been shown as a potential threat... her actions time and again show she has feelings for Armaan and she may like blurt it out anytime... though she is a good friend she cant have a control over her emotions... while i feel bad for niki at times i also get angry as she tries to assert herself in Armaan's life, as though she finds it next to impossible to see a changed Armaan in front of her eyes, from whom she had no expectations wad so ever....
both the characters are amazing for the story, as they give the story a necessary push with respect to the AR story....