Here is a detailed explanation of the Sharia perspective on purchasing animals for Qurbani:
1) If there are more needy people, then it is preferable to choose an animal with more meat. Otherwise, a fat and well-fed animal with a high price and good quality meat is preferable.
2) If the price of a goat is equal to one-seventh of a large animal like a cow, and the amount of meat is also equal, then it is preferable to buy a goat. Similarly, sacrificing a sheep is preferable to sacrificing a goat, and sacrificing a female animal is preferable to sacrificing a male animal.
3) Sacrificing an animal with a higher price is better. If the price of two animals is equal, but one of them seems to have more meat than the other, then the animal with more meat is better and preferable.
4) If someone is financially affluent enough to buy two moderate animals, then they should buy two moderate animals instead of purchasing one fat and well-fed animal for the same price, because fulfilling two Wajibaat is always better than fulfilling one Wajib.