Heroes of Might and Magic II is the best.
HoMM III expanded on II and is nearly as good.
HoMM IV has the best heroes, and is still very good, but not as good as II and III.
HoMM I is the worst, but still a decent game.
I have HoMM V but have not played it yet, and I do not have HoMM VI.
Thanks for the giveaway.