User blog comment:Blappp/AoE II Tech Tree revamp/@comment-31031245-20170203114226/@comment-27198062-20170203122017

yeah imma go with the majority here, both solutions are fine for me.

another advantage of ages in columns is, that they are (in my opinion) easier to expand (for non-Castle unique units one simply has to add another row which is easier than another column, main reason) and also easier to edit (with the arrows and unit evolution, not that much of a big deal, as it only has to be done once):

| style="text-align: center;"|
 * style="text-align: center;"|→
 * style="text-align: center;"|Crossbowmanavailable.png
 * style="text-align: center;"|→
 * style="text-align: center;"|Arbalestavailable.png

whereas when ages are in columns the source code is sorted by age and the arrows ↓ are less neat to add.

also when scrolling down, the ages for all buildings are aligned vertically, making it easier to spot which units and technologies are available at a certain age.

main advantage of ages in rows in my opinion is that it is familiar, as it is like it is in-game.