Mechanically, MTW/VI is a much better game. The SP campaign has staying power even after a year and a half. With STW/MI/WE, everyone seemed bored with the SP campaign after about a month or two. SP STW topics on these forums virtually disappeared after that time. Not so with MTW/VI.

For atmosphere and game immersion, STW/MI/WE was the superior game. From the seasons to the various cut-scenes to the throne room to the emmissaries, the game pulled you into its world.