They both seem to strong for their costs to me. Draw up to 6 is very strong, especially attached to actions.
I'm leaning toward the reactiony version. Do you think it could work at $5? Or, maybe keep the $4 cost and partially detach the +Action.
Nook 2.0$4 -- Action-Reaction
Choose one: Draw up to 6 cards in hand, or +1 Action, discard your hand and draw up to 4 cards in hand.
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When you discard this other than from play, you may reveal this and put it on top of your deck instead.
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This version would give you one mulligan, and you need to work to make it have actions. As this is, I'm not sure the ability to mulligan and self-combo a bit compares favorably to Watchtower.