best-loved vs pet

best-loved is not a noun while pet is a noun.

Word	Noun	Adjective	Verb	Adverb
best-loved	No	Yes	No	No
pet	Yes	Yes	Yes	No

As adjectives, best-loved and pet are synonyms defined as:

best-loved and pet: preferred above all others and treated with partiality

Other synonyms of best-loved include favored, favorite, favoured, favourite, preferent, preferred.

best-loved (noun)	pet (noun)
	a domesticated animal kept for companionship or amusement
	a fit of petulance or sulkiness (especially at what is felt to be a slight)
	a special loved one

best-loved (adjective)	pet (adjective)
preferred above all others and treated with partiality	preferred above all others and treated with partiality

best-loved (verb)	pet (verb)
	stroke or caress gently
	stroke or caress in an erotic manner, as during lovemaking