Wolfhound APC (Apocalypse)
While most road vehicles should be avoided, the APC is a nice vehicle to use for transporting troops around the city early on. It has enough equipment space and passenger slots to transport cargo and aliens while still carrying a respectable crew and it lets you save your air vehicles for combating alien ships.
Be careful using one of these for troop transport while there is an air skirmish taking place. Because it only takes one stray shot from an enemy craft to take out the road under it, thus killing all of its passengers in the process. It's best only to use one of these when cityscape combat is not expected, if the APC can travel a route away from the battle, or after the UFOs have fled back into the gates.
Though you can arm a very formidable set of light weapons on the APC, it is best kept well away from combat for the reason mentioned earlier.
Note that all Wolfhound APCs come standard issue with a cargo module. This standard issue cargo module is a bit sticky and might take a few tries to remove if you need to other modules into it.