Ubisoft games have some common characteristics across different series. Far Cry, Ghost Recon, Assassin's Creed share similar traits. Its called the Ubisoft open world for a reason, and although recently they have changed it up a little bit their games still retain the characteristic quantity of missions and content with little variety. Its not always the case though, and looking at the past some of their games, from said series did have a strong identity and unique characteristics which made them iconic and intriguing for different reasons across the games.
Ghost Recon wasn't open world till last year and games like AW 2 and FS were good tactile shooters. Assassin's Creed pretty much invented the Ubisoft open world and as a result felt like a fresh take on the open world genre when it was ruled by GTA and the likes and top down RPGs. Far Cry has strong core mechanics which make the guns feel satisfying. Rainbow Six has retained its tactile feel with modern titles like Vegas and Siege. Prince of Persia always had amazing platforming and puzzles with an interesting atmosphere and soundtrack.
Assassin's Creed, for all its flaws, is my favourite Ubisoft series. AC 2 is my second favourite open world game, Brotherhood is among my favourites, 4 was a good pirate game, Unity had a very immersive city with amazing detail and graphics and filled with characters making the world feel alive and so many detailed interiors where you could go and Syndicate had a beautiful city as well. Its too bad the series has changed direction to a more generic approach but the older titles will always be in my memory <3