Hurm, this is tricky, since I enjoy Indomitable and Reinhardt a lot, but for different reasons, and they bring different things to the table, but nothing that isn't covered by someone else. Also, Reinhardt isn't quite as powerful as some of the others in this campaign, because he's like 20 points or so beneath a lot of the others I think.
Ultimately, I'll go with Indomitable because he hasn't really done much that was that cool yet. Reinhardt dropped a Lantern with minimal assistance, and killed a fairly important Invasion leader. Plus I plan to use him more when I get to my eventual Vanguard game-might have him join/work with UNISON at the behest of his grandfather. Talos 2.0 will have to wait.