I'd go for the A770 over the B580. 16GB > 12GB, and that makes a difference for a lot of AI workloads.
An older 3060 12GB is also a better option than the B580. It runs around $280, and has much better compatibility (and, likely, better performance).
What I'd love to see on all of these are specs on idle power. I don't mind the 5090 approaching a gigawatt peak, but I want to know what it's doing the rest of the time sitting under my desk when I just have a few windows open and am typing a document.
An older 3060 12GB is also a better option than the B580. It runs around $280, and has much better compatibility (and, likely, better performance).
What I'd love to see on all of these are specs on idle power. I don't mind the 5090 approaching a gigawatt peak, but I want to know what it's doing the rest of the time sitting under my desk when I just have a few windows open and am typing a document.