Well actually there is a problem here with most of the logos (and it is not to criticise the other designs), but most apart from 2, 3, 5, 6 and 8, go against the rules of design on the site here. Logos are supposed to be Vector graphics, which means that we cannot just paste in a raster graphic like you have provided, but have to redraw it if it is to be used. There are different reasons for this, but they all have to do with ensuring that you get a quality product.
Oddly enough the moderator has not interfered here (they might remove them).
Below is quoted from the site here:
Your work must be created in a vector program such as Adobe Illustrator, and the final files MUST be delivered in .EPS format. Photoshop is not for logos and.
Admins & Mods will remove entries without notice for not following the above submission rules.