Ever since the first Apple Silicon in 2020 there are questions all over the internet about how much memory a person might need. IMO, it is important to consider what one does. One person may do very heavy duty stuff and need more, but another person may do lighter things and need less. You just need to investigate and then decide based on what you will use the computer for, not what some other person uses their computer for. It will help you to figure out what applies to your case and what doesn't. Of course, I realize that some people just want a maxed out computer even if they will not actually make good use of all the extra memory, more cores, etc. Nothing wrong with that, get what you want. 
This is a well done video that stresses the computers to compare performance:
16GB vs 32GB RAM M1 Pro MacBook: REAL-LIFE Comparison
And this good video is doing photo stuff using huge files (56gb file in Photoshop, making humongous panoramas in Lightroom, big HDR merge, etc.) -- which I do not do:
Why Photographer should upgrade MacBook Pro 2021 RAM to 32 GB for Pro Photo Workflow? 16 VS 32 GB
This is the interesting video that I posted earlier. No one would load their computer down with so many programs, heavy duty programs, running at the same time, but it gives an extreme stress test to see how things work out.
16GB vs 32GB RAM M1 Pro MacBook - Multitasking RAM TEST
The takeaway for me is that for my uses it looks like 16gb will be fine so that is what I ordered on 3/8 (14" M1 Pro MacBook Pro base model). I use Lightroom, Photoshop, and Topaz programs. Of course, browser, etc. too. No video editing. All my photo files are 20mp or smaller. I don't make big panoramas. I rarely even use Photoshop and when I do it is just for some light things, usually with no layers. During the first 14 days if it looks like 16gb was not the right choice then I can return it.
One thing I will note from all these videos is that although they show in the system monitor the memory pressure with the 16gb and 32gb computers and sometimes the 16gb has more and the 16gb also has more swapping, in most cases both computers were still performing very similarly and were both responsive. Very fast SSDs and memory. Therefore, for me, memory pressure and swapping amounts are interesting technical things to know, but the bottom line is whether the computer is working well. I don't really care about the memory pressure and swapping if the only way to really know it is happening is having to look at the system monitor.
I pretty often see people say they like to buy and use the same computer for 7-10 years. Or their digital camera. I usually don't go that way myself though when tech is changing fairly fast. I usually buy for what I can use NOW and for the next year or two, but not way down the road -- too hazy to see that far into the future anyway.
With Apple Silicon I am thinking that 16gb on an M1 Pro will be good for me for quite awhile. In a couple of years there may be an M3 or M2 Pro or whatever and other good stuff. I would then probably want to update for many reasons, not just to get more memory.
For people who do want to use it for 7-10 years and don't care about the M3, M4, M5, etc. and other likely good stuff Apple will come out with in those 7-10 years then spending $4k, $5k, $10k now and then a few years later still be using an old, outdated, relatively slow Mac compared to the then current models is fine. Different strokes for different folks.
Here are 2 more good videos by a photographer so it is good see the focus more on that rather than just the many generic benchmarks:
M1 Pro Macbook Photography Review - 16GB Ram Mistake?
Lightroom Tests on the M1 PRO MacBook: A Photographer’s Dream!
There are now 4 variations of the M1 SoC. Awhile back I made a chart to help me keep track of them while I was trying to decide which Mac to order. I have added the M1 Ultra now. Note, this shows all the various options with each one, but for a particular computer all those options may not exist.
The single core performance is the same for all 4 of these SoCs, but the multi-core performance varies depending on how many cores (and if the software really takes advantage of them). Note that the memory speed though is different so in real life even the single core performance can vary since some programs are making lots more memory accesses than others.
You will note that while the M1 and M1 Pro (one variation) both have 8 CPU cores, the M1 Pro has 2 more performance cores and 2 less efficiency cores.
Feel free to correct anything I got wrong in the chart.
This is a well done video that stresses the computers to compare performance:
16GB vs 32GB RAM M1 Pro MacBook: REAL-LIFE Comparison
And this good video is doing photo stuff using huge files (56gb file in Photoshop, making humongous panoramas in Lightroom, big HDR merge, etc.) -- which I do not do:
Why Photographer should upgrade MacBook Pro 2021 RAM to 32 GB for Pro Photo Workflow? 16 VS 32 GB
This is the interesting video that I posted earlier. No one would load their computer down with so many programs, heavy duty programs, running at the same time, but it gives an extreme stress test to see how things work out.
16GB vs 32GB RAM M1 Pro MacBook - Multitasking RAM TEST
The takeaway for me is that for my uses it looks like 16gb will be fine so that is what I ordered on 3/8 (14" M1 Pro MacBook Pro base model). I use Lightroom, Photoshop, and Topaz programs. Of course, browser, etc. too. No video editing. All my photo files are 20mp or smaller. I don't make big panoramas. I rarely even use Photoshop and when I do it is just for some light things, usually with no layers. During the first 14 days if it looks like 16gb was not the right choice then I can return it.
One thing I will note from all these videos is that although they show in the system monitor the memory pressure with the 16gb and 32gb computers and sometimes the 16gb has more and the 16gb also has more swapping, in most cases both computers were still performing very similarly and were both responsive. Very fast SSDs and memory. Therefore, for me, memory pressure and swapping amounts are interesting technical things to know, but the bottom line is whether the computer is working well. I don't really care about the memory pressure and swapping if the only way to really know it is happening is having to look at the system monitor.
I pretty often see people say they like to buy and use the same computer for 7-10 years. Or their digital camera. I usually don't go that way myself though when tech is changing fairly fast. I usually buy for what I can use NOW and for the next year or two, but not way down the road -- too hazy to see that far into the future anyway.
With Apple Silicon I am thinking that 16gb on an M1 Pro will be good for me for quite awhile. In a couple of years there may be an M3 or M2 Pro or whatever and other good stuff. I would then probably want to update for many reasons, not just to get more memory.
For people who do want to use it for 7-10 years and don't care about the M3, M4, M5, etc. and other likely good stuff Apple will come out with in those 7-10 years then spending $4k, $5k, $10k now and then a few years later still be using an old, outdated, relatively slow Mac compared to the then current models is fine. Different strokes for different folks.
Here are 2 more good videos by a photographer so it is good see the focus more on that rather than just the many generic benchmarks:
M1 Pro Macbook Photography Review - 16GB Ram Mistake?
Lightroom Tests on the M1 PRO MacBook: A Photographer’s Dream!
There are now 4 variations of the M1 SoC. Awhile back I made a chart to help me keep track of them while I was trying to decide which Mac to order. I have added the M1 Ultra now. Note, this shows all the various options with each one, but for a particular computer all those options may not exist.
The single core performance is the same for all 4 of these SoCs, but the multi-core performance varies depending on how many cores (and if the software really takes advantage of them). Note that the memory speed though is different so in real life even the single core performance can vary since some programs are making lots more memory accesses than others.
You will note that while the M1 and M1 Pro (one variation) both have 8 CPU cores, the M1 Pro has 2 more performance cores and 2 less efficiency cores.
Feel free to correct anything I got wrong in the chart.
