As a conclusion, both are common. You have to understand the difference. In English you have same sense, I think. 机の上に写真があります。 ＝There is a picture on the desk. In this case, we emphasis on 'picture'. We know there is something on the desk and ask what? 写真は机の上にあります。 ＝The picture is on the desk. In this case, we emphasis on 'on the desk(place)'. We know there is a picture and ask where? By the way, We can arrange these sentences. 田中さんは事務所にいます。 田中さんが事務所にいます。 In this case, we have to discuss the difference between は　and が. Generally, “Aは" means "Talking about A." 　 On the other hand, “Aが” means “Not B, not C, but A.” If you know more deeply, you can check this site (although it is difficult), http://www.kazandogakukai.com/_d269122444.htm

@Yuta.Y The answer is exactly what I want. Thank you very much!