- To AoN or not to AoN? -

AoN, or "All or Nothing" armour schemes are a type of layout in which entire sections of a ship are replaced with hollow portions, allowing more of a ship's percentage  to be concentrated in smaller areas, therefore allowing higher concentrations (and therefore thicker) armour for those areas. If the hollow portion of a ship is struck by a shell, it often does little to no damage to a ship. At first, AoN armour seems to e clearly superior to ships without it, but there are some notable disadvantages to AoN layouts.

What are the different advantages and disadvantages to AoN armour?

Let's start with the advantages. AoN armour, on average, allows for more armour to be placed over the areas of a ship that are high concrete count such as the deck (the top), the belt (the side), and the keel (the side of the ship that is below the waterline). This means that it takes significantly longer for sections of the ship to be "drilled" (the armour on that area being completely blown away, leaving the weak insides to be hit with much more damage). It also means that (coal) torpedoes will go right under the AoN sections of a ship without exploding at all. Finally, large areas of the ship are completely hollow, meaning that damage to those areas will deplete almost none of the ship's health percentage.

Now for the disadvantages, and there are a lot of them. First off, AoN sections mean that there is a whole new surface of a ship that can be struck; the exposed core of a ship that is open to the hollow sections. Often, these areas are lightly armoured, if at all, meaning that if those areas are struck, they can deal significantly more damage than had a shell hit an armoured portion of the ship. Secondly, with much of a ship's mass being concentrated in so few spots, damage to those areas tends to deplete more percentage of a ship's health, regardless of how armoured it is. Finally, AoN ships often have to be longer or wider than non-AoN ships.

Is either superior to the other?

For almost a year, AoN armour was almost standard for dreadnoughts and many cruisers. It was believed to be overwhelmingly superior to non-AoN layouts up until a couple months ago, when more efficient armour layouts for non-AoN ships became more mainstream. 

Superiority for one or the other is subjective and often dependent on a playstyle or doctrine. Experimentation on different methods and designs is paramount to discovering more efficient ways of creating one's own ship that fits them or their nation the best.