This is something I've been saying for years.
Slater is the type of player who will take a 20 point victory and turn it into a 40 point thrashing. That's why 9 times out of 10 he will be better for Australia than Hunt would be, as we are generally so far ahead of everyone else that we play that the question is simply what margin of victory will there be. He is a fantastic individual player that is capable of magic. And to be quite honest, with the way Origin is going he may even be better in that in quite a few games because of the apparent gulf in quality.
But in a close match I'd take Hunt any day of the week. He's arguably the second best under the high ball in the NRL (Falou is obviously the best), getting better and better at playing that vital part in backline movements which constantly result in a 3 on 2 out wide, and is also a great communicator. Not many people talk about his communication, but it's one of his greatest assets. In defence he is constantly yelling and pointing, telling his team-mates exactly where they should be. In attack he's doing the same, letting others know where he wants them. And when his team is down, he's generally in there clapping people on the back and geeing them up. Little things, but they add up.
Yes, Hunt's less likely to create a moment of magic to win the match, but he's more likely to make the team as a whole play better in a close match.