I got into Civilization rather late with their fifth entry. I was hesitant because as I get older I need more time to game than I do new titles. Still I picked up six with all DLC during the last sale. I have to say I am liking the changes. It was good to wait because Civ does need its DLCs to feel complete.
On a side note, it runs quite nice on the Steam Deck (In desktop mode docked)
5 is superior imo, it’s more simple to understand but has a lot to master. It’s more visually appealing too, Civ 6 throws so much extra crap at you.
5 is more depth from simple mechanics. 6 is adding mechanics to try and make depth. I’d recommend 5 for sure, though 2K are kind of scummy and put 6 on discounts to try and force players into that and no longer really put Civ 5 on sale cause they know people would rather buy that.