I don't rate Fury anywhere near as highly as many. I think he is a very good heavyweight but far from this all-time great that his fans will have you believe. Your summation of his best wins is bang on the money. I rate Wilder lower than I rate Fury. Wilder's fans keep banging on about him being one of the top 2 or 3 hardest punching heavyweights in history. It's just not true. He has power for sure but his record is literally a can factory.
Don't mind who wins but I feel Zhang has more ways to win. Wilder I think is a spent force and probably there for the taking.
I'm very biased here and it's a very easy choice. Zhang's the man for me. One of my favourite current heavyweights. I like his personality and hope he wins this in big style ( let's be honest, it is fun watching Wilder getting timbered) and cements some more big paydays before he retires. If the belts do get fragmented, and if it's then possible, I'd like to see him get a world title strap fight before he calls it a day.
Like Fury stating in a interview, he would hang his sister if she was promiscuous. Wilder wanting to take a boxers life in the ring is one sick statement, but Fury saying he'd hang his sister is taking it to another level.
Unless there is some sort of punch-power measuring device, it's really hard to say who hits harder. It's all anecdotal. Anecdotally, anyone who's sparred with Wilder acknowledges he can hit like a mule. Of course there is a lot more to boxing that just the raw ability to hit with power. It's in those other areas that Wilder falls short.