mmkw, like with your thread about Siddharth's movies I answer that I don't have a favourite.
But I can tell that the very first SRK AND Hindi movie I watched was Mohabbatein. It may have been a coincidence (no, I don't believe in coincidences) that the main lead was a teacher, the movie set in a school, and the main device a kind of 'battle' between a progressive teacher and an authoritarian principal. I instantly knew (at first sight of SRK's facial expression) that the young teacher had an agenda and I also liked his rebellious and daring mind.
I'm a teacher myself, very pro kids and know how it is to work against set rules, so apart from all the novelty I experienced (and that the movie reminded me of old German musical-movies), I got an instant liking for the Raj Aryan character.
Coincidently (not), the next Hindi movies I was given to watch had been K3G, Main Hoon Na, Lagaan, VeerZaara and Dil Se...so, you see, I hadn't only an intense dose of SRK movies but also of YRF ones.