I did go back and play Civ 3 and Civ 4 for the first time in a while, maybe ten or fifteen years for Civ 3. They're still playable and I enjoyed them overall, however, stacks of doom and unit spam that were largely eliminated with Civ 5 are not something I missed at all. At its core I think Civ 4 is a better game than later civs and it had a strong mod scene that gives it some major life beyond its age. If only it had that new combat system! Civ 3 on the other hand there are a few things I like I wish the series had kept, but by and large if you have Civ 4 you don't need Civ 3. I can't imagine playing Civ 3 outside of a every decade jives and giggles play-through.
Maybe coming close is Medieval: Total War. It's one of my favorite games and there's a lot I still love about it. For example, the personality traits and dynasty just don't have the same impact in later games. It's such a fun challenge to have have my ruler be an empire-building Charlemagne type whose military victories and infrastructure works make him a beloved living legend, then his son is some depraved half-wit and as soon as he's on the throne half the empire rebels.
But those battle graphics are starting to look like fuzzy indecipherable pixels. Sometimes I wonder do I think the cavalry look like a dude or a horse, or do I just remember that's what that particular pattern of dots were? And the reinforcement mechanic in the older Total War games is just dumb. You lose a unit? A new one will join the fray. Enemy unit loses a unit? A new one will join the fray. The second army comes in piecemeal that way because of the limits on how many units you can control. I always hated that and the advance in technology where entire second or third armies can now show up and be controlled all at once is just so much better and makes going back to the older games that much rougher.