I work for SkyDemon, so that's my bias...
Its the data that matters. The most important thing by far is presenting the data in a way that the pilot feels comfortable using. Getting unambiguous information into the pilots eyes (and therefore brain) should be the aim of the game, and if some people feel more comfortable with a scanned paper chart because that is what they are used to, then that is totally fine.
The chart format is pretty much irrelevant legally unless you are dealing with a country that specifically mandates you carry a paper copy of the national air authority's chosen chart format.
Otherwise, look for correct, well updated data from a trusted source, presented in a way that helps you navigate effectively under pressure.
Interestingly, "official" paper charts cannot always pass this test... They are often out of date by the time they hit the shelves, and it has become commonplace for pilots to use old charts because they are still "good enough".
Last edited by Bobby Hart; 3rd Oct 2013 at 09:53.
Reason: clarification