Long time lurker, first time poster!

I'm starting to plan a RTW for next autumn. Right now, the itinerary is LHR/SFO/AKL/SYD/HKG/SIN/NRT/LHR, but I'm open to switching things around if y'all have any advice

In particular, SFO is only included because I had to stop in the US somewhere, I'd be happy to visit somewhere else if the flights are good. But I'm also not tied to AKL, SYD or NRT - I'd be happy to do other stops in those countries (although I do want to visit each of those countries, and I'd prefer east coast for Oz). SIN, Kuala Lumpur, Indonesia? I just want to get away!

But what I AM sure about is that I want comfortable flights. I'm happy to spring for business, but would rather not have to pay for first. I don't mind what the seats are like for flights under 2hrs, I just like to be able to lean back a bit if the flight is under 4hrs. But once it goes over that, I'm looking for a lie-flat seat at a minimum, ideally a flat bed.

So, with that in mind, what would you recommend? Which carriers should I look for, and is there anyone to avoid? Should I change the routing anywhere? Are the 777s on CX nicer than the 747s on QF (and how can I work out which version of the 777 it would be)? How can I make this trip as comfortable as possible, basically?

Thanks!