I don't think there is any skill that is obviously the most important skill. One of the aspects I like best about HD recruiting is that there are tradeoffs involved in every player.
In your example, I would rather have the 50-100 guy than the 80-60 guy as my perimeter scorer. The 80-60 guy is good enough shooting outside that I won't cringe every time I see him hoisting a 3 in the pbp. The 50-100 guy will stretch defenses. I would compare it this way: if you were an NBA GM and needed a perimeter scorer, would you rather have JJ Redick or Victor Oladipo?
Rather than fetishizing any particular attribute as the most important, first come up with a minimum acceptable rating for each position that you are recruiting, given your offense/defense. What is the minimum passing rating that your PG needs to have? (hint: the answer is different if you run motion or fastbreak). What is the minimum rebounding rating for your PF? (hint: if you run zone, that number is higher than if you run man).
Find players who meet your minimums and then ask yourself, what can this player do well? The difference between the 80-60 and 50-100 guy is that the 80-60 doesn't hurt you in any areas, but also doesn't do anything incredibly well. That's less valuable than it sounds because he doesn't put any stress on the opposing defense. The 50-100 guy, they need to know where he is on the floor, because if they leave him open, he will kill them.
I'm not saying that I have always followed this advice, but I have always regretted the times that I didn't. On my best teams, every player was recruited to fill a specific role and had at least one thing that they were tremendous at, even if it was just rebounding.