What's the best "Once Upon a Time in...." movie?

With "Once Upon a Time in Hollywood" coming out on home media, I got to thinking, what's the best "Once Upon a Time..." movie out there? There's a lot of them too. You have the big ones, "OUaTi America" (1984), "OUaTi the West" (1968), "OUaTi China" with Jet Li (1991), and "OUaTi Mexico", plus a whole host more that I've never even heard of.

Which one is the best, or at least, your favorite?