>>96400521
Well, none of the superheavies are practical for the same reason we don't have gigatnaks IRl and big boats are always followed by an entire fleet of AA boats: Big slow things die to planes. And I'm not counting any of the self-propelled artillery pieces like the Arquitors because at that point we're not examining the tank, just the gun that would work just as well mounted on the ground and crewed by 5 guardsmen. So we're left with... Sicarans, Kratos, and the transports. I'm gonna go with Land Raider, probably one of the variants like explorator or Achilles. Virtually indestructible, best AI in the market, enough firepower to melt tanks, etc. The big honkin' ramp to disgorge angry men with axes is the impractical part, but that's solved by EWAR equipment or just another gun like the variants