So I've been chugging along with this elderly 15" 2012 MacBook Pro 9,1 for... uh... well, since 2012. It's been upgraded to about the best I can upgrade it: 16GB RAM, dual 2TB SSDs, new battery, new thermal paste, and so on. It's also the higher-end model with the 2.6Ghz i7 and the full 1GB of GT 650M VRAM. It's my mission-critical machine: I use it for daily tasks, email and web browsing and whatnot, but also for troubleshooting and device setup (I work IT and it goes with me), and even some audio and video editing. It gets used a lot , is what I'm saying. The machine's gone from whatever it originally came with (what was that, Lion?!) to Catalina, and when that was no longer supported but I needed a secure modern OS to continue IT'ing, I used OCLP to carry on with unsanctioned Big Sur, Monterey, and, for the past year, Ventura. All three of the newer OSes with OCLP ran better on this machine than Catalina did. GeekBench benchmarks are even slightly ...
Opinions on OS Versions for 2012 MBP.