I wouldn't say that one is superior to the other in terms of construction/quality. They probably are remarkably similar in that regard. Both represent the pinnacle of English RTW construction. It comes down to that which is more suitable for you.
Pigskin is typical softer, more flexible and much less able to hold a shape in the long run than calf leathers. For that particular shoe I personally would stick with a hatch or pin grain if you want a texture. I think of pig skin as being appropriate for less formal styles such as moccasin construction, split toes, etc. etc.