Well they all can do 'auto' equally well - so if just comparing them straight up on capabilities of the sensors and cameras themselves, leaving out the user, lens, or adjusting settings, the NEX has by far better capabilities and higher IQ across a broader range of photography. It's the only one using a large APS-C sensor like DSLRs, which will demolish the small sensor P&S camera you mentioned when it comes to low light/high ISO work...and overall more resolution with larger photosites and lots of flexibility. Do remember though, you have to get lenses for the NEX...so the versatility depends on which lenses you decide to get for it. And it will clearly be larger with all but the 16mm pancake lens attached. The G12 will also be bulkier and larger than the other two.
The S95 and LX5 have good IQ and higher ISO ability than most P&S models, due to their 1/1.7 sensors vs most compact cameras' 1/2.5 sensors...but the NEX's APS-C sensor is positively huge by comparison - and it's in an entirely different category and capability.
Sony DSLR-A580 / Sony 18-250mm / Minolta 50mm F1.7 / Sigma 30mm F1.4 / Tamron 10-24mm / Tamron 150-600mm / Tamron 90mm F2.8 macro / Minolta 300mm F4 APO
Sony A6000 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses