APC and Tanks
Strengths: APCs are used to transport an infantry unit quickly. The APC should be used to get the infantry unit to a far property for capture and can also be used to supply mobile field units with additional ammunition and gas (even air and sea units). Simply park your APC adjacent to any unit and select "supply" to supply all adjacent units with gas and ammunition. This will also be done automatically at the beginning of a turn if an APC is adjacent to a friendly unit.
Maximize your infantry's movement by positioning your APC at the edge of your infantry's movement range. Then move the infantry onto the APC then move the APC to its max range and drop off the infantry on the far side. The infantry just moved a very far distance in a single turn!
Weaknesses: Has no attack, which leaves it very vulnerable. The APC has decent armor but will still not withstand much punishment from mechs and any tank or indirect-fire unit.
Strengths: At less than half the price of a medium tank, the standard tank can complete most battle tasks nicely. The tank features a secondary machine gun to use against infantry; and it's highly effective. With ammunition, the tank is a dominating force against recons and indirect-fire units, and works well against an anti-air unit. Don't bother attacking a medium tank or neotank of equal hitpoint strength.
Weaknesses: Avoid indirect-fire, as you should with any unit, and beware of stronger tanks, the medium and neotank. Attacking mechs also have an advantage over the tank.
Strengths: A much more powerful version of the standard tank. The medium tank also features a machine gun and can be an effective infantry killer. It also dominates recons, anti-airs, tanks, indirect-fire units, and anti-air units. You will suffer more damage in an attack against a neotank, however.
Weaknesses: Don't fight neotanks! And steer clear of indirect-fire barrages, which will definitely punish the medium tank.
Strengths: The expensive granddaddy of tanks is strong against every other ground unit type.
Weaknesses: Don't be within range of indirect-fire weapons!