Well, there's always going to be a lot to disagree with on lists like these. That's to be expected. However...putting Civ IV: Colonization above Alpha Centauri is just plain ridiculous. As much as I loved the original Colonization, Civ4Col was a sub-par game, deeply flawed in both in design and execution. Alpha Centauri, on the other hand, is a gem of game design and atmosphere, probably the most memorable of any TBS I have played. I would have put it right at the top of the list.
Civ VI I can kind of understand. I personally think both Civ V and Civ IV are better, but I see why they would go with VI for the list. It has its strengths, and it's the newest and shiniest one in the series.