Sleeping Dogs DLCs that you want..
- Nightmare in North Point
- Zodiac Tournament
- Year of the Snake
- Wheels of Fury
Those are the DLCs adding some playtime and not just cosmetic aspects to the game. The Wheels of Fury being a crazy vehicle should be activated later in your playtime not to make it too easy at the start by having the big monster wheels to start the game.
These, plus the SWAT pack adds a bunch of police missions and the Street Racer pack adds 3 races.