I'm looking to buy a used mac for my daughter who is entering high school in the fall. I tend to compare benchmarks to try to find a good mix of value and performance, but that's apparently not enough. Apple is clearly not focussed on CPU benchmarks when obsoleting older macs, so I'm wondering exactly what hardware components Apple is focussing on? Metal 2 compatibility for GPU, obviously. Any other technologies that I should be certain it supports? I would hope she could get a couple major OS X upgrades with a decent second-hand mac.