I think there’s more luck involved in drafting so I’d go with the pro scouting.
People act like these late round picks that hit are the work of genius scouts when it’s more random than that. Amateur scouting is more impactful at the top of the draft but you won’t always be there. You can always improve the team through FA/trades
This is really the argument for Pro Scouting being more important. And it's a very fair one. The draft really is far more of a crapshoot than people give credence to. A lot more luck involved. There's also a huge influence of "development" vs purely amateur "scouting".
That, and recent Cup Winners like Florida and Vegas being built heavily around pro scouting acquisitions, free agents, trades, etc.
Though in the case of Vegas, obviously for early success with an Expansion Team, Pro Scouting is going to factor more heavily. That's an outlier case though, and not strictly applicable to the typical team situation.
In the case of Florida...an unusually high proportion of high profile Trade/Free Agent acquisitions, but still lean heavily on some core "drafted" players as well. They aren't doing anything without Barkov for instance, and you don't get Barkovs anywhere other than the draft.
The other aspect to this as well though, is that you typically have to draft reasonably well, just to get the "trade chips" to make some of those bigtime deals. Like...Florida aren't getting Tkachuk, if they don't draft Huberdeau and find and develop Weegar up from the Amateur level.
That's where i think good Amateur Scouting and Development are still slightly more critical in typical team situations. To get those "core players" or desirable trade chips to swap for "cornerstone players" you can't typically get any other way. But it's really hard to draw a line there, because good Pro Scouting is still massively important. You still have to even know who to go after to supplement things.