1-4 was the golden age. Every iteration from 1-4 got better. 5 was normal age. 6 is the dark ages.
Having said that, I’ve tried going back to civ4 and I just cant. It’s over. It was a contemporary feeling of that time. I’m just hoping they get back on track with civ7.
This sums up my view. Agree with OP that Civ IV was tedious in the end game espececially on larger maps but it's still fun to play and engaging. Civ I-III great in their time but graphics too painfully dated now - would love a Civ III remaster! Civ VI for me was an epic fail. Hoping better for Civ VII but have moved on for now to HumanKind, Old World and Shadow Empires for 4X.