graphic display connundrum

[sagefr0g]

ran into a problem, that i can't understand, while trying to graph various advantage play data in excel.
in excel you can format an axis, either by a 'default' automatic method, or you can choose logarithmic.
the conundrum to me is that sometimes, the graph appears proper, just using the 'default' settings and sometimes not so proper, and sometimes the graph appears proper using the logarithmic setting and sometimes not.
so i guess my question is when is it proper to just use the default setting and when is it proper to use the logarithmic setting.
see examples below for the impact of formatting the the x-axis on the (right side) using the two different settings.
the big difference is how the advantage (blue curve) appears.
that graph using logarithmic appears more correct to me.

 

[sagefr0g]

ahhh k, think the problem is solved.
when the advantage 'involves' any negative numbers, the axis can't be be treated as logarithmic in excel and the automatic default setting works appropriately, trying to use logarithmic in the case of negative advantage numbers gives a haywire looking graph.
but when the advantage only 'involves' positive numbers, the axis can be treated as logarithmic in excel and provides an appropriate graph. not sure why just automatic default setting wont always work ok, all of the time. i think it has to do with the scale (intensity) of the curve and amount of data.
a bit of a 'quirk' of excel's me thinks, sort of.
this lady tries to explain this sort of thing, in this link: http://www.forbes.com/sites/naomirobbins/2012/01/19/when-should-i-use-logarithmic-scales-in-my-charts-and-graphs/#4d21916a3cd8