I think the reserve Titans are very strong particularly in Attrition.
But Map Hack is just crazy. It gives you the ability to see every enemy in your area, which not only makes it super easy to kill them with no risk, but also makes it much easier to plan out certain routes.
It's honestly a silly card and I don't think it should be in the game. Unlike the Titan cards, there's no real counter to the Map Hack card if the player using it is halfway competent.
I still prefer Chaingun in gametypes that aren't LTS. It's excellent at cutting down pilots, including the pesky ones who hound you from rooftops. And with the Accelerator + Damage Core + Rocket Salvo, you can inflict a significant amount of damage on other Titans in a short time, especially by targeting critical sections.