Which of the sentences is more commonly used used by native speakers?

This is a 25-storey building.

This is a 25 story building. (AmE)

I don't think storyed is a word in any dictionary

I did find this info:

storeyed (BrE) = storied (AmE) as in
This is a 25 storied building..

I've never heard anybody use either 'storeyed' or 'storied' before.

From the Free Dictionary:

storeyed ('st??r?d) or storied

adj
1. (Architecture)
a. having a storey or storeys

b. (in combination): a two-storeyed house.

I had never noticed that AmE spells it story until I typed my reply and my spell-check flagged storey.

Although it's in the dictionary, storeyed is not widely used.
Storied has a second meaning, "associated with many stories or legends", which is the more common usage of the word.

So Americans and British use "25-storey/story building".

tamguatlayI have a feeling that "This is a 25-storeyed building" is used by the British.

Not very often. A search in the British National Corpus (BNC) turned up:
12 matches for one storey and none for one storeyed.
29 matches for single storey, and none for single storeyed.
44 matches for two storey, and only one for two storeyed.
29 matches fo