IS3

At stock, the tank is quite useless. You'll find you'll lose my 1v1 battles with other Tier VIII heavies. But, once the BL-9 is researched, you will find that you're dominance over other Tier VIII heavies is more than assured. I have the IS-3 and i was getting more than frustrated with it at stock, but once you have the BL-9, you can not only damage tier X's, but i've had multiple tier X's rounds ricochet off the pike armour. Get to the BL-9 ASAP and you'll start playing to what it's worth.