Well, I actually tested a M4 Max 16" and it was faster in some areas and some slower than my M1 pro. Ie disk speed was actually slower on the M4. I can wait another generation.
The M4 Max has faster write speeds but slower read speed than the M1 Max, but the difference isn't going to be anything you'll notice in daily use. Compared to the M1 Pro, the M4 Max is faster in both read/write speed. I went from an M3 Max to an M4 Pro and the system is noticeably quicker and more responsive. I lose a media encoding engine but it doesn't really impact my workflow.
The difference between M4 Max and M1 Pro should be huge, especially in single-core performance making the overall system feel snappier. M4 Max also has two encoding engines versus one on M1 Pro for video editing. You also get faster neural engines that aid with photo editing. M4 Max also has brighter screen, faster memory bandwidth, faster GPUs with ray-tracing support, AV1 decode engine, Thunderbolt 5, available nano-texture screen, better webcam, the list goes on and on. The M1 Pro is still good, but it's strange you discount the M4 Max based on a slightly slower disk benchmark metric against all the other advantages.
The only tangible difference I could see the M4 Max losing to an M1 Pro is probably heat and real-world battery life -- the M4 Max uses more power under load and produces more heat, but honestly a new M4 Max will probably still have better battery life than a 3-year-old M1 Pro MBP 16.
This is MaxTech's disk benchmark of a 16" MBP with M1 Pro:
