Comment: Arduino Uno (Score 1) 228
I started with bare bones AVR. I switched to Arduino. I could see from online community support Arduino would jump start my experience. A year or so later I have made several higher ended projects including the electronic payload for a near space balloon. I would have not achieved so much so quickly without Arduino and the community support.
One can still go small with Arduino (Nano, Micro, etc) and one can go barebones as well: http://arduino.cc/en/Main/Standalone.
I generally prototype with the Uno and switch to the Nano or barebones when moving beyond the prototype stage.