I've had two Nvidia cards die on me, and AMD cards have been reliable. So, I'm not even going to consider buying Nvidia again, unless we start looking at Nvidia getting twice the performance in most games for the same amount of money. I know everyone's experience is different, and Nvidia is reliable for most people, but I can only go by personal experience. Brands get only one or two chances from me before I write them off as too unreliable to buy, despite how well they may perform.
Watch Dogs is running well for me, and both my GPU and CPU are AMD. I'm not concerned with comparisons, because I'm not in the market for a new card. All I know is that I'm happy with my performance and the way the game looks.
Judging by those benchmarks, Watch Dogs is horribly optimized (the system requirements seem to agree).
+1. Like you said everyone has their personal preference for these things. I'm the opposite of you. I've had radeon cards die on me, while my next two Nvidia cards are still with me. My GTX 480 is in a box and my gtx 660 Ti is still running strong from day 1. It's just all based on personal experiences and preferences with Drivers and how the UI runs and updates for most people.
All in all, just go with what you have known and like best everyone!
I'd say give it a try. You'll never know if you like the game or not until you get into it yourself. I remember buying Batman Arkham Asylum and just had it on my PC for months. I kept putting it off 'cause I knew I didn't like superheroes in general, and that kind of third person action game wasn't my thing. But, after all the hype, I decided to give it a try, beat it in a few days and enjoyed the hell out of it.