Leghorn,
Ignore all advice and get what you like the look of
Yes there are differences between some breeds, and yes our GOS tend to be fattier after 6 months
if you overfeed, but so will other breeds, and yes coloured pigs don't burn as easily as pink pigs, and yes and yes and yes..... Answer is if there was one good pig to get, we all have it, and the other breeds would not exist
As HH says, the differences between breeds are insignificant to the taste of outdoor reared proper pork.
So choose what you fancy, and enjoy !
Of course you should now ignore my advice as I've just told you to ignore all advice !