You should finalize the location based on location of your office. Do you know where is it?
Al Waab is decent place when compared to Umm Ghuwalina however access to Al Waab could be crowded during peak hours. Kind of same for Umm Ghuwalina as well but Umm Ghuwalina has some variation. Some of the streets are very congested and way people park, its very hard for two cars to pass.
So if your office is near to Alwaab, that will be a better choice.