This is highly subjective and anecdotal, but I find OSX to use a lot of RAM.
The in-OS memory compression helps, but when I still had a 16GB Macbook Pro, the system always found a way to use up all of the RAM to the point that the compression would kick in to handle the overage over my physical memory.
My habits aren't any different in terms of extraneous windows/apps open on Windows, and I rarely hit 100% RAM utilization on my 16GB Windows machine.
The system should use all the RAM. You paid for RAM, why have it sit there unused? As long as the next user process gets the RAM it asks for, I want the system to use all my RAM to cache everything.
Edit: even to the point of compressing pages, since it's faster to uncompress them than fetch from disk.
The in-OS memory compression helps, but when I still had a 16GB Macbook Pro, the system always found a way to use up all of the RAM to the point that the compression would kick in to handle the overage over my physical memory.
My habits aren't any different in terms of extraneous windows/apps open on Windows, and I rarely hit 100% RAM utilization on my 16GB Windows machine.