Both Canon EF16-35L and 24-70L are very solid and expensive lens because of the large aperture (f/2.8).   Most lenses become fully extended at their longest focal length setting and their lens hoods travel along with this extension.  However, the 24-70L lens “reverse extends” - it becomes longest at 24mm.  That’s why the 24-70L lens has such a intimidating/huge hood.  It is just too heavy and large for me.  

Since a full-frame sensor can offer low noise up to ISO 3200, if your sole purpose of large aperture is for blurring background for portrait, the 85mm/1.2 L lens ($1,950) is your best bet.

By the way all Canon L lenses (with a red strip) come with lens hood without extra charge.

Here is the most complete and best review about the Canon 四君子  vs the better-known 三劍客 lenses: