Is there a standout amongst these camera choices?

Please do not exaggerate! The G12 can and the G15 will shoot perfectly well indoors sans flash, if you are conscious about how to use it: bump up the ISO and don't expect to go away from the wide end. I have thousands of excellent G7, G9, G11, and G12 shots made without flash in dimly lit museums the world over.

No camera is perfect.

SX230 has advantageous in size and features. For some, the pros will outweigh the cons of slow lens and small sensor.

The G series has an excellent track record of build quality (loose screw issues on the G9, though). "Breaking at any moment" is a red herring.