Not a huge number of tanks in the Star Wars universe; everything is walkers or speeders.
But the Republic TX tank from the Clone Wars video game was a pretty awesome tank. Highly maneuverable and heavily armed, way more capable than the AAT.
Though, the AAT's armaments still prove to be superior. The main guns of the TX were two light cannons and a set of missile launchers, while the AAT had its super heavy main gun, two light cannons, two anti-personnel blasters, and six tube launchers with a selection between three different types of ammunition.