Currently, the poll in this thread has favored GGG to 23 votes and zero votes for Murata. Indeed, GGG is really the crowd favorite wherever I read about this match.
According to their record GGG has the experience and knockout advantage compared to Murata. GGG's record is 41-1 (36 KOs) while Murata's record is 16-2 (13 KOs). Both their KO rate have frankly small gaps, 88% and 81% respectively. So that leaves GGG to have the upper hand in this fight but he will have to endure and overcome the challenge of fighting the opponent in his own country where Murata is viewed as hero and a gold medalist in boxing during the olympics.
GGG has more experience than Murata. He is a great boxer and I like to see his precise punching again although there might be difference now because of his age compared to his performance few years ago, but I believe he still have the power to win.
Yes, that one thing we need to look at his fight, whether GGG at 40 has still the same punching power because he can get old overnight. Obviously, he has the experience here and face a lot of boxers, great one than Murata.
On the other side, Murata is younger and a tough fighter as well but it seems he is lacking on defensive skills based on my observation in his previous fights. Anyway since it will be held on Japan, certainly he will have a great support from his countrymen.
Murata is also a champion, although he didn't have the caliber of fighters that GGG face, still he has some in his arsenal that can be pull an upset. Specially that this fight will be held on his home country, he will simply not going to get down that easy and will fight to get a win as well.