Generally, I use the syntax `[..., 0]` when `ndim > 4`. It is more convenient but it is less informative and more error prone. For example here, you know immediatly that the data is 3D. If the data becomes 4D because of an error, then an error will be raised here.

Plus, in the particular case of imshow, I like to know exactly which dimensions are displayed.

So I prefer `[:, :, 0]` in this case.