Do you have the budget for the 2019 model? If so, then wait for that to be released this fall.
If you don't have the budget or can't wait then you really should post what your budget is.
The 2012 is definitely not a good purchase at this point. Unless you want to hack it (never a good idea for a work machine) then you'll be stuck on Mojave with CPUs that are potentially vulnerable to MDS attacks (they're so old that Intel won't release patches). At a minimum you'd need to disable hyperthreading, which would definitely affect video editing workflows. And even then, I think the CPU(s) would still be somewhat vulnerable.
The trashcan is also a poor value. Yes, way overpriced and furthermore, it's five years old now and will only be supported in future macOS versions for maybe two more years. It's also not really upgradeable, aside from memory and SSDs. Its biggest issue is that it uses custom GPUs. They've had reliability issues in the past and you can't really upgrade them (just replace with the same thing). eGPU is currently an option, but only via a hack that Apple could disable at any time.
What about the iMac Pro? Or if you need to go cheaper you could consider a Mac Mini or 5K iMac with an eGPU to get better NLE performance.