RTW Roundup: Best business class seats
The Best (tie): South African Airways and United Airlines (new seats)
You just can't beat lie-flat, horizontal. South African has advantages because these are seriously huge seats. As wide as the regular La-Z-Boy business class seats, but the rows are so far apart from each other that you have to undo your seatbelt to reach the seat pocket in front of you. They were a bit lumpy when in horizontal flat bed mode.
United's new seats are a winner. They're equally comfy sitting up as well as lying down horizontal. They are narrower than South African's seats though, and I'd suggest upper deck window on the 747 in order to have seat-side storage. Otherwise, there's no storage in or around these seats for takeoff or landing.
The Rest
Singapore Airlines has flat beds on some airplanes, angled lie-flat on others, and recliner-type seats on yet other flights. I had the latter two BKK-SIN-SYD. While I did get some good sleep on the angled lie-flat seats, I did feel like I had to occasionally readjust because I slid down towards the floor.
Turkish Airlines also has angled seats on their aircraft, but I might actually like them better than Singapore's angled lie-flat seats. They still have the slight upwards slant around the thighs so you don't slide down and get that wedgie.