Thierry,
#2 and #4 stand out to me for their composition and tone, I like them a lot.
Although in #4 it looks like the building has a slight lean, yet the column does not...perhaps that is my perception?
Thanks Kay. You are right concerning the #4.perhaps that's due to a lens distorsion.
It looks like you have perspective distortion combined with a tilt in #4 (if it isn't cropped):
this makes the building lean to the left, and it seems as if the right pillar is straight. But, both pillars should be leaning to the left, i.e. the centre of the photo (again, if no crop)
Remco