Vanquish got me, but I was secretly very pumped to play it.
Biggest contendor would be the Saints Row games. I got 2 and 3 free on PS Plus, then I saw the ridiculousness of SR4, and decided I needed to play them. Two months before SR4 was released, I beat SR2 in a month, and then SR3 in the next month, right in time for SR4 to be released. I then dove in SR4. Good lord. Before I started playing any of them, I saw them as a shameless GTA clone. While that may have been true for one, it started fading away in 2, and by 3, it was it's own comepletely unqiue beast. SUre, it's an open world city. Yea you are a criminal. Yea you get guns, and can kill anyone. That is where the similarites end. SR3 shines, and 4 puts a superhero gloss of paint over it. From it's jokes, to gameplay mechanics, to the variety, so the services in place to just make the game more fun for the player. It's great. I had so much fun with my time with the Saints games, which I am very thankful for, because I now know they are far, FAR more than a "GTA Clone". I will be day 1'ing whatever their next game is, no doubt.