Hi Stevish, I am currently facing the same issue as well. Have been trying all the methods that I found online and those that you posted. I had also contacted my host company but the technical support personnel can’t solve it as well.
I also tried changing theme, modifying the permission of the wp-content folder to 777 as well (I had switch it back to 755 due to security issues). Still, none of these work.
Perhaps this is a bug of WP 3.9? I don’t have any issue uploading images in the previous version, but I can’t recall exactly which version is that. I installed an older version (3.8.1) to see if it works but the same problem occur.