The camera you have with you...
They say the best camera is the one you have with you.
Early in the days of digital photography I reluctantly carried a bulky, heavy camera. Eventually I upgraded to a more compact model with fewer features to keep with me, and a DSLR for serious shoots. The compact one was still noticeable in my pocket.
Throughout this progression I've had a smartphone with a camera. At first it was a crummy VGA camera that I never used. The original iPhone was a big improvement, but still mediocre. My use of it increased as I upgraded to the 3g and 3GS, and somewhere along the line I stopped carrying the point-n-shoot. The iPhone 4 introduced a great camera and 720p video, and my use of it skyrocketed.
With the 4S, I am constantly impressed with its photo and video quality, and I leave my other cameras home more often than not. Recently on vacation with my iPhone 4S and DSLR, I often took better photos with my phone. The colors and sharpness are excellent, and best of all, it's always in my pocket.