>>714771414The third is when everything peaked, all lessons learned from 1 and 2 were implemented to produce the best game in the series.
4 is good I suppose and a bit experimental but the studio was on the verge of bankruptcy, it was their last hurrah and it shows.
5 and everything else forward was done after the franchise was sold to ubisoft and it shows, entries range from ok to just bad.
You don't have to worry too much about the story of 1 and 2 if that concerns you. 1 was very basic 2 was war of succession between 2 brothers.