Saif Ali Khan is known to have the best chemistry with every actress he pairs up with. He made an almost perfect pair with Rani Mukhejee in Hum Tum, he shared a sizzling chemistry with Preity Zinta in Salaam Namastey. Even in Race, Saif Ali Khans chemistry with Bipasha Basu was worth raving about. When he romances a woman on screen, it looks as if he is really involved with her. This is a hallmark of a great actor.
Your vote on this answer has already been received
I think at present Hritek Roshan has a best chemistrry with girls as there is no rumours about him linking with any of the top heroine of the Film Industry. In the past Manoj Kumar has got the best chemistry as he too like Hritik Roshan has been never linked with any top of the heroine in those days.