Analog isolation vs Digital Isolation
Any reason not to just use a miniature PCB mount mains transformer at the input of the thing and measure the secondary? Instant isolation, no need for power on the non iso side of the barrier, readily available with any safety certification you like and cheap.... 

Now if you are trying to measure detailed harmonics or fast transient events this may not cut it, but for many applications a miniature PCB mount mains transformer is entirely appropriate, a modest load resistor on the secondary will help with performance in most cases. 

As to the digital isolation, depending on the speed you need, a jellybean 6N137 will do 30Kbaud or so, and there are some very small micros these days to encode the ADC output into something async that will pass the opto... 

On the analogue side, do not discount things like the IL300, old school but still very useful. 

And yea, chip vendors tend to publish white papers favouring their solutions, in much the same was as the marketing department write the front page of the datasheet....