I always carry two cameras when I leave the house.
One must be small, fast and digital for easy snapshots and video. The second ought to have a larger sensor for better quality images. I arrived at this combination because I used to regret not having a good quality camera when I needed one, like when girlfriends suddenly decide they are okay with "artistic" photos.
In recent years, the small digital is either the Ricoh GR or Panasonic LX7. In past years, it has been the Ricoh GRD III, and assorted Canon S and G series cameras.
The large sensor camera is the Panasonic GM1 with the Olympus 25/1.8, which makes for a very small kit. When the mood takes me, I'll take the Fuji X100, the M9 + 50mm Summicron or 50mm Zeiss Sonnar, or maybe a Sigma DP1/2/M, Zeiss Ikon or Contax T3.
I prefer gear that is small and lightweight; for a few years, I carried a Canon 30D, and then a 5D Mark II. Then I began to yearn for lighter gear, so I carried the M9 and three lenses, until that became a bit heavy, too. Now I'm down to two tiny cameras as my daily carry, with occasional forays into larger cameras if the situation calls for it. I'm very happy that current technology allows me to have excellent image quality in such a small footprint.