Imam al-Shafi'i (may Allah have mercy on him) said: "Since sacrifices are merely blood by which nearness (to Allah) is sought, the best blood (i.e. a fine animal) is more beloved to me. Some of the exegetes hold that the words of Allah, the Mighty and Majestic: 'That (is the command), and whoever honours the symbols of Allah' [Surah al-Hajj: 32] refer to making the sacrificial animal fat (well-fed) and fine."
Imam al-Shafi'i (may Allah have mercy on him) said: "The Messenger of Allah (peace and blessings be upon him) was asked which slave (to free) is best. He (peace and blessings be upon him) said: 'The one that is highest in price and most precious (and cherished) to its owners.'"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / Q19081