The Gang Hideout and Convoy Fixer Contracts are underrated. They can really get out of hand to the point of hilarity, and the game shines the most in those scenarios. The mechanics allow for some really badass moments that I think have been glossed over in favor of arguing about visual downgrades. It's the first time in a long while a game has reminded me so much of GTA3's "block the street to kill the target" style of gameplay.
Or just snipe him.
Or screw it up and end up in a chase.
Or blow his head off with a shotgun and blackout the city to escape.
Or set up an IED trap.
Or have the police show up and shoot it out with your enemies while you flank them and silently knock out the the target before getting away with car stealth.
They're great, you can pretty much do them in whichever way you please. I'm actually pretty happy with the side missions in Watch Dogs, there's some genuine variety there (besides the crimes which are formulaic and exactly the same every time).