EYES
The conventions of the street photography purist caution against making photographs of people looking into the camera. They argue, when a subject looks into the lens, it makes the photographer part of the picture. They're right, the subject's recognition of the camera changes the photo. But every time a photographer chooses a subject, chooses a frame and chooses a moment to activate the shutter he/she is becoming part of the picture. There is a reason some photographers win Pulitzer Prizes while others produce vernacular snapshots. In both cases the photographers are part of the images they produce.
Shakespeare said, The eyes are the windows to your soul. Eyes in the lens engage the camera. The very thing that repels the purist often times is the soul of the photograph; that thing that makes the image most compelling. I'll side with the eyes.