I have plenty of experience with wigs and ponytails. Each have their own issues, with price being the primary consideration. Buy what you can afford.
Human hair is superior to synthetic. Synthetic hair tends to tangle easily, and when brushed hard, stretches and no longer looks like hair. Many hair care products cannot be used on synthetic hair, and dryers cannot be used unless the hair specifically says heat resistant.
Human hair wigs are much more expensive. Since you don't plan to "wear" it, I might suggest a used wig, you might save some money. For wig care, search online for tips and hints.
I like ponytails now. They have their own issues, when the band holding it doesn't keep it from shedding. Also, the price skyrockets as they get longer.
Hope this helps (probably just made it more confusing.)