Best tank for Palp lead, Vader, Nihilus and Thrawn?

Yep. They did. DN or Thrawn for the most part. Thrawn is one of the few DS toons with utility. But Ls is full of toons with utility or synergy. DS had a few strong toons that occasionally LS squads would plug in. DS has nothing that compares to GK, r2, etc, etc, and all the LS toons that have huge utility. Thankfully, maybe, hopefully, the overlords have seen their error and will be continuing on correcting it to once again bring balance to the universe.