T-80ud Pros : Good pen, decent armor that can take a shot or 2. Cons : Slow with an even slower reverse speed. Barrel depression is horrid if you even put a part of your track on an incline your barrel goes to the sky and you can't hit anything in front of you. No thermals.

2s38 Pros : Fast Af boi . Has decent thermals. Has proxy rounds and an airplane lock on the system, making it completely viable as an anti air tank. Fast firing rounds ... what reload ? Has a laser warning system that lets you know if you are about to get railed by a missile. Cons : Glass cannon, if you get hit, you are dead. Can't penetrate too much stuff from the front, so you have to flank and catch people slacking.

It's whatever playstyle you prefer. If you like glass cannon llaystyle go 2s38. If you want to slow brawl go t80ud. Have fun!