I've pre-ordered one of them, and it's not available yet, so you know my answer.
When an anti-piracy method is affecting the game for people who legitimately bought it and causing other people not to buy the game, there is obviously something wrong with it!
Don't think you can compare the two, both published by Ubisoft, don't think they're trying to compete with each other.
Watch Dogs is looking awesome so far
Watch Dogs has a lot of potential with the hacking aspect the problem is how they convert that into gameplay. All the trailers I've seen look cool but the gameplay looks maybe to simplistic.
Ok... AC 4 BF is a sweet game and probably the best AC of all time, but saying it's the best is like saying the Wii U is next gen.
What about Thief, Infamous: Second Son, Daylight, Destiny, Dragon Age: Inquisition, Tom Clancy's The Division, etc.
Most of these will be "true" next gen titles where AC is not a next gen title by a loooooooooooong shot. Watchdogs look great but I prefer Tom Clancy's The Division over it.