Titans.
I pick Titans not only for the Titans, but for the entire Wizard army. 3 shooters, 2 with no melee penalty, a hero that gainst gobs of knowledge stat for more castings, etc.
A wizard army with Mass Haste is hard to beat if they have shooters in large numbers. Unless you know mass dispel.... but the AI sure sucks at casting that.
(And dragons? Wizard army eats dragons for lunch if they're in equal numbers with the titans, provided you have accumulated plenty of halflings and archmages. Doubt not the power of a giant stack of halflings, for it is second only to Skeletons)