Great post. I like your framing when thinking about comparing across generations. Training, coaching, strength and conditioning, data, analysis have all improved vastly.

Is the best hitter in MLB history the guy who faced pitchers who used to throw 4 games a week and throw 150 pitches a game or the guy who faces 3 different rested, specialist pitchers throwing at their peak every single game?

It really seems unreasonable to compare and almost impossible to find the right answer so I think you have to base it on who was most dominant compared to their peers at the time they played and for how many years they were able to dominate their peers.