Frankly, I find Iran to be less threatening than Saudi Arabia. Of course, I don't actually live in the Middle East (and I'm sure our Israeli allies disagree with my opinion).
But the Saudi / Iran relationship has always struck me as odd. The main issue is that the US truly messed up our relationship with Iran in the 1970s and 1980s (and they reciprocated: Iran-Contra affair and all that).
But as bad as the hostages / attacks / etc. etc. got between the US and Iran during the Cold War... Al Qaeda literally launched the 9/11 attacks from Saudi Arabia, and the infamous hijackers were primarily from Saudi Arabia. The militant form of Wahhabism was Osama Bin Laden's religion and is strongly based in that area.
I mean, we somehow kept a good relationship with the Princes of Saudi Arabia, and I understand that the leadership of that country does cooperate with us. But for all the bluster about "Islamic Extremist Terror", Mr. Trump bowed down and participated in swords dances last time he went into Saudi Arabia... never once bringing up the issue publicly the last time he had a chance.
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All in all, I'm happy that the general US Population is waking up to the fact that our "ally" in the middle east deserves far more scrutiny than we've been giving them so far.
I don't necessarily want our relationship to go sour. But we need a serious and stern talking to Saudi Arabia in general, that we the USA do not approve of a lot of the things that country does. Frankly, those princes have far too cozy a relationship with Wahhabism for me to be comfortable with, and their human rights record is pretty bad as well (see the primary story about Jamal Khashoggi)