Xanos, Kaneq, Allice, Elric, Taurus, Torsen, Leon, Goblin Squad, Tanya, Mortus, Tareth, Aqua, Gale, Lucius, Bloodspear, Ember, Flora, Boomer, Esabel, Ariel, Magdor, Cyana, Lumos, Mog, Mariana, Osiris, Ulfang, and Solomon
Depends what team builds your looking for. For campaign you could probably use Elric, Taurus, Xanos, Kaneq, and Flora for a lot of it.
Heroes you want to forget about completely for now, IMHO: Torsen, Leon, Goblin Squad, Mortus, Aqua, Gale, Lucius, Ember, Boomer, Ariel, Magdor, Lumos, Mariana, Ulfang, and Soloman. Some of those I left out can be useful in some situation, like Prophecy Pool when you open it, (for instance Cyana for the DoT one.) Bloodspear is good for high damage single target modes, such as Hall of Legends and raid bosses.
I assume you're free to play, so I would recommend trying to get Zem from the Crucible of Fire as a replacement tank. Nilya and from regular arena. Garrick from Epic arena. Malrath from Hall of Legends shop. Jasmine from guild shop to replace Flora.