I would love to see a Wonder Woman. Any version of her but I can only imagine how cool she would look.
Also, I may be alone here but I would love to see HT tackle the Smallville JLA. Green Arrow, Black Canary and Aquaman are must haves. Cyborg, Impulse I could do without but they would still be cool to have. Clark would be cool just to get a sixth scale Tom Welling sculpt. Their costume redesign (specifically GA and Aquaman) are pretty impressive for a TV show budget.
As already said, a Keaton Batman is a must as well as his cohorts of villains. And a Reeve Superman, Zod, Ursa and Non would rock.