Regarding RTXA2000 6GB vs. RTXA4000 16GB, it is more of a question what is available.

RTXA2000 ~40MHs/70W, ~1.75W/MHs, no extra power needed & have not tried reducing power yet.
RTXA4000 ~58MHs/115W, ~1.98W/MHs (philipma1957 settings)

RTXA4000 costs 2X, so that also needs to be considered.

But as I said, I could get RTXA2000, RTXA4000 is MIA currently and I doubt I will get more of those RTXA2000s until next year.

And these cards will not be used for mining for long, they will go to actual workstation PCs :-)