Aamir Khan: The original chocolate-boy of Bollywood & the best-looking Khan (at least back when all Khans were young & good-looking without make-up). Decent-enough actor, somehow shot into "brilliant" actor status thanks to his knack of choosing cheesy scripts. Now, the consummate marketer, he'd give IIM-MBA's a run for their money.
Note: Sarfarosh & RDB don't automatically imply he is patriotic (he might be the most patriotic of all the Khans but that's not much to go by, is it? ;)
Saif Ali Khan: Easily the least successful of all the Khans, he has exactly one good movie to his credit (where he didn't make an ass of himself, which is why I excluded Dil Chahta Hai). His only other notable Bollywood-success is hooking up with a 100-times more successful Kareena Kapoor.
Most Notable guest appearance: "The Buck Stops Here", starring Shirtless Khan.
Salman Khan: No shi(r)t. Aishwarya Rai. Drunk-driving. Katrina Kaif. Period.
Shah Rukh Khan: Easily the best actor among the Khans, sadly stopped acting in good movies after 2000. Currently trying very hard to emulate Aamir Khan in marketing, but falls flat. Where Aamir slickly markets his movies with/without controversy, this guy just Kkkk...Khan't do it without making noise.
Seinfeld-esque
14 years ago