Vehicles equipped with a heavy base will excel at land-based activities. Compared to a hoverbase, heavy turrets will barely slow them down, operations (e.g. terraforming) will be finished twice as fast, and they can take considerably more beating until they expire. Heavy base vehicles cannot stand on water alone, however, and are hindered by mountainous terrain.
Unless the terrain is extremely mountainous it is generally a good idea to use this base type (or catamaran base) for offensive vehicles. Other turret types may benefit from either, depending on the scenario. On flat planets with little water, heavy bases are the ideal choice for all turret types, assuming resources and research state allow it.