I'm theoretically confused when it comes to the question; upgrade to FF, or get very wide lens?
I have a 70D and mostly use the canon 24-105mm f/4 L lens. The issue I have with this lens is the crop on the 70D, which gives me (x1.6) a focal length of 38-168mm and fixed aperture of +/- f/6.
What is (and why) the better option (don't mind the price, Im looking for a theoretical answer): get a FF camera which loses the crop, and thus gets wider shots. Or, get wider lenses: to get a 'real' 24mm shot, I would need to have a 15mm lens...
So, a focal length of approx. 10mm wouldn't even by viable...
What are your thoughts?
EDIT: Reformulation of question
Suppose I'm positioned and have a camera pointing into a city street. Now, I know that theoretically, I could obtain a shot with a specific angle with (1) an aps-c camera with some lens on focal length X, or (2) a ff camera with some lens on focal length X'. Both delivering me the same shot. (where the focal length X is cropped by factor 1.6 in case of my 70D)
Aside from the price, and the lens inherent properties such as sharpness etc. Is there any significant theoretical reason for one te better then the other?
Would the same shot by (1) and (2) have the same perspective? FoV? and/or other properties?