With hex grids, you can choose to arrange the tiles with the pointy sides up, so that you can move along the west-east axis, or you can arrange them with an edge up, so that you can move along the north-south axis.
"Horizontal" or pointy-side-up hex grid:
"Vertical" or flat-side-up hex grid:
According to this page, the vertical alignment is "by far the most popular" in pen-and-paper RPGs, but it doesn't explain why. This blog post also mentions both varieties but again gives no reason to use one or the other.
And if you look at some PC games using hexes, it seems both have their adherents
Horizontal: Heroes of Might and Magic series (except V), Civilization V , ...
Vertical: Panzer General and many similar wargames, Battle for Wesnoth, ...
But what are the main reasons for choosing for a vertical or horizontal layout of hex grids?
I'm looking for objective advantages and disadvantages in terms of data structures, graphics, gameplay etc, not personal preferences. Or is it really inconsequential which orientation you choose?