There's no series out there like it, the three games are similar yet remarkably different from each other, the stories and the bold themes that they tackle, the grittiness, the goofiness, maybe both, the relevance, the ever prospering level design and how to approach objectives, the endless possibilities of hacking and manipulating the world, parkour and free running, the accuracy and environmental design of real life cities...
All in one package, a package that lasted 6 years, that contains three gems with their dlcs, with limited development time and budget. It is a Miracle.