ImgBB most often I used it myself, I noticed that after two reloads of the page, some of the img managed to show up. I did an update of one
thread and half of the images were visible.
You are right. It's the problem with ImgBB. I do not use it but I use imgur all the time. The size of a file also is an issue for not displaying an image properly.
Imgur and Postimage are my two current choices for hosting images, so there's no harm in leaving the other hosting site right?
For me Postimage is better than Imgur. The best thing about Postimage, you can use it on TOR browser, that's the biggest advantage for me. Anway, this topic was useful to find a good solution for image hosting for me.