Carrying Skis on a Backpack

Hi,

I have noticed 3 different ways that are used to carry skis with a
backpack (there may be a few others as well):

1. Diagonal carry - Skis are lashed together and then tied to
backpack extending from lower left to upper right (or vice versa).

2. Straight horizontal - Guide I was with in Austria used this
method, as above but skis tied to top of pack and lie horizontal.

3. What I call "A frame" - Skis individually attached vertically to
sides of pack, and tied together at the tips.

What are the advantages and disadvantages of each of these methods, as
I want to purchase a new pack that is designed for the optimal
carrying method.

Many thanks.

Craig