I am very happy with my ThinkTANK Glass Limo backpack. However, it has a snug fit for Canon 500mm F4 lens in case the rounded padding is used. For €4 I found seamster and now I have two pieces instead of one round padding. So I only use upper side now and it is much easier to put the lens in and get out of the bag. Maybe next time ThinkTANK?
Here’s the direct link for Glass Limo bag in Amazon