Seems to me that there is a singular difference between McVay and Kyle Shanahan that has me strongly favoring McVay.
BOTH are extremely detail oriented. That's a very good thing.
However, how it's manifested is very different and that makes all the difference.
McVay, as Cooley noted, imparts immense amounts of knowledge and details as befits a coach of much more age and experience. As a player, he felt empowered...almost cheated that he didn't have more time with him as a coach. Thus, the detail is imparted in an empowering way, put in to help the player succeed in their assignment which helps the team succeed. It's an inside out approach which in the "age of accountability" where players in a team sport are often penalized or rewarded for things far beyond their control, having a coach build them up and have that be the genesis of the team's success is going to build not only loyalty, but that critical synergy that gets those 2nd and 3rd tier guys to step in when the starters get injured.
Shanahan, on the other hand, is more of a taskmaster. As has been noted, he will drill...and drill...and drill...until guys get it right. The knowledge is imparted, not so much to build up the player, but because it's the right way to execute the play or the offense. It's the right way and players will need to get on board with the right way. Not that there isn't success in that. There most definitely is. Or can be. However, as we've seen with McDaniels, that "right way" mentality doesn't translate to every situation and can really alienate players. If that alienates core players, that's a problem. One thing that hasn't been mentioned is that Shanahan has been really hard on Matt Ryan. REALLY HARD. Is that the best learning environment for Jared Goff? Not saying the kid's not tough. We've seen that he is physically tough. However, if you look at Sonny Dykes' mentality, he was an "encourager", not a taskmaster. Frankly, taskmasters can wear a person's butt out. It gets tired after a while.
That, to me, seems to be the difference.
McVay seems to be a prodigy in more ways than just Xs and Os, more than just technique...all of which are extraordinary. He seems to be a prodigy in HOW he connects not only with players, many of whom are older than he is, but also much older coaches who seem to gravitate to him and respect him.
When it came time to first address the team this year, iirc, it wasn't Jay Gruden who did it...it was Sean McVay. The fact that the first address, often the address that sets the tone for the entire year was delegated to someone SO YOUNG speaks volumes to me, considering that Gruden should have wanted that privilege and he's got a former HC in Callahan who would have done well giving that as well.
When we talk about the pitfalls of going the Coordinator route, this is where McVay shines and Shanahan has issues. Because NO ONE questions McVay's leadership whereas Shanahan has these flags where one must question if he will get buy in from everyone.
Will Shanahan's attempt to bring in a "culture of winning" be a "my way or the highway" attitude? It seems so, by all accounts and that's very concerning.
Otoh, it seems that McVay's approach is about empowering players to be the best possible versions of themselves which not only appeals to their self-interest in their Not For Long career, but also their team interests.
I still think that Asshole Face is the BEST option for this Rams team. Bar NONE.
However, if the Rams are not going to entertain that, McVay, to me, is the second best option.
I still like Kyle Shanahan. A lot. However, if he were hired, I'd be concerned about his staff and the team morale once they actually started installs and they got a taste of his idea of "the right way"....
No, I don't put O'Brien above any of these folks. McDaniels isn't a consideration for me. Patricia is, tho after Shanahan, and I think if he brought in Vrabel, the LB coach of the Texans, iirc, as the DC, that'd be a heckuva defensive staff at the top. Before I got any more excited about Patricia, I'd have to see all his offensive coaches...OC, OL, QB, RB, WR, TE... We need quality at all of those spots.
But the idea that Vrabel might be a DC...soon. That's about right, actually. His LBs play lights out.