Top would be Green Lantern. They do have a show coming and I'm sure it will be expensive, but I'm sure it's not going to be unlimited budget territory. Others:

Justice League International (really doesn't need that high of a budget but I want it regardless of budget)
Dresden Files
Harry Potter (made into movies but would be great as a series)
World War Z (made into a movie but would be much better as a series and faithfully adapted)
Pokemon Adventures (adaptation of the manga - the adventures of Ash doesn't follow the story or tone of the manga)
Days Gone
BioShock
Left 4 Dead
Star Wars (Old Republic Era)