The Sony's are nice but as soon as you want a fast prime or a telephoto you suddenly end up with a huge camera setup again, you might as well just go for an entry model DSLR. Even the slow 18-55mm dwarfs the cameras. Limited lens choice to date
Nikon 1 are lighting fast in all aspects and the IQ is top notch given the sensor size. Entry level orientated bodies so far and not many lenses either.
M43, mature, plenty of lenses, some nice small fast primes. The older bodies are cheap but have relative poor IQ, the new models with the 16MP sony sensor appear to rock. with both Olympus and Panasonic making lenses, as well as 3rd party manufactures like sigma and SLR magic due to the more open standards, there should be plenty of lenses to come. They have now figured out how to make high quality lenses in small sizes. M43 got a lot more attractive in he last 6 months.
The rest are all a bit limited in some way, even if the cameras are nice. Samsung CSC line is very nice but how quijcly can they release new models and lenses? Same goes for Fuji X. The Canon M has an aging sensor and the so called hybrid Af with phase detection is really bad.