well im no expert on this but here's what i think.
* 1st poster looks the most professional. Nice see-through pattern on the right, as well as the over riding thumbnails give a more postery kind of feeling.
* 2nd poster: Maybe you could zoom out a little, so that the air conditioner on the wall will not be as visible. Or just photoshop it out
* 3rd: Have you thought of moving a little to the left when taking the photo, so that the white wall part under the stairs and above the letter AZA will not show.
hope that helps