What is a good lead?

I've been lurking in this sub for a couple of months now, and I keep seeing rants and questions about leads.

I'm diving in this new lead world and was wondering:

What makes a good lead?

Could you break down the five most important factors that define a high-quality lead?

(Ofc, I know the basics (thanks to the rants lol) like making sure leads aren’t resold and avoiding fake or disconnected contacts.

But what about other factors? Does age, price, or something else play a big role?