Frankly, there is a huge difference between URLs:
I agree, I was just trying to emphasize the problem.
I am probably not the right person to tell you what is good/best for SEO, there are others well more professional in this to answer the question. From customer point of view I'd rather have
with canonical url to point to the main url on all variations. To me this follows the site structure.
Why don't you have it both ways and allow admin to select?
Another way would be to include the catid in the clean url instead as a parameter but again you may hear it is bed
Or you can have all 3 as options and admin can select how to have it... Just a thought