Definitely eyes... 你 can tell something (practically everything) when 你 stare at someone's eyes. 你 can also tell if they're lying 或者 not. 你 can tell what they are feeling at the moment when 你 look right into their eyes. Unless you're clueless, of course...
The eyes, just because 你 can tell how someone feels 或者 what personality they have (sometimes, personality isn't always that easy to decode) just 由 looking into their eyes. Especially because when I see a person 或者 creature that makes me sad 或者 scared, it's almost always because of the look in their eyes.
