I played for Boone County, I've seen Boone and Holmes 10+ times this year each and I went to the State tournament for every game that Holmes played.
I have zero reason to be biased in the favor of Holmes and against Boone.
And I can say that I have serious doubts that Boone would have beaten Christian County and I'm extremely doubtful they could have beaten Lex Cath.
When you play regional opponents you have a significant advantage in scouting your opponent (as opposed to teams across the state) and you have a much better idea of what the local teams like to do, how to stop them and how best to exploit their weaknesses for yourself to prosper.
When you get to Rupp, it's basically 100% about player personnel and talent. It becomes less about strategy and more about who has the best players, not only because there is less knowledge of your opponent to be gained from seeing them play throughout the year, but once you get passed the first round you have less than 1 day to even prepare for said opponent, and of course in the finals you have less than 8 hours.
Having said that, I don't really like this debate because it's waaaay too hypothetical. Who knows how well kids like Gabbard and McFarland would have handled the big stage and how much they would have stepped up (or not at all). They may have excelled there and played their best ball of the year or they may not have been able to handle it at all.
Every single year you see teams underachieve and overachieve in Rupp, for various reasons.
Boone had a very nice team this year, but I think looking at it on the surface they would have had a significant athletic disadvantage against teams like Christian Co and Lex Cath.