I'd say the best bang for the buck "old" MacBook Pro is the 2015. It fully supports Monterey. The 2015 has lots of ports, and has the scissor keyboard. After 2015, they went to the butterfly keyboard, which is problematic. The SSD can be upgraded, either with OEM Apple / Samsung SSDs or else with 3rd party NVMe drives (albeit with potential compatibility issues), but be aware the memory is soldered so it can't be upgraded. Also, the anti-glare coating can wear off ("delamination") so be careful to inspect the screen (or screen pictures) when purchasing. The battery is also a biotch to replace since it's glued in.
I purchased one last year for a relatively cheap price, with a perfect screen and a new battery/top case. I then added a larger OEM SSD for cheap. Since then I've noticed they've dropped significantly in price, probably partially because they don't officially support Ventura, and the OEM SSDs have dropped in price too. They are still more expensive than NVMe SSDs, but the OEM SSDs don't have any compatibility issues obviously.
That said, my next used Mac laptop purchase (for my kid) will likely be a M1 MacBook Air. Those things are starting to come down a bit in price too on the used market, and there may be some decent deals in 2023 and beyond.