2 thoughts
1) If you are worried about old power sucking machines nodes in a box work well:
https://bitcointalk.org/index.php?topic=5364113 and they really don't use that much power after IBD:
Thar is what a full mynodebtc on a RPi pulls through the USB. Obviously at the power pack at the wall you will be 110V/220V but still only a couple of watts.
2) If you are not running other things like a block explorer, electrs, lightning node. 1TB will last a good long time. If you want to do more, yes 2TB
-Dave