Ah, right. I do know (Or believe) Indoril is really big in the Mournhold area, so I wasn't sure if you could join it in Tribunal or what.
I'd really like to advise one or the other, cause of late-house-quest rewards, but spoilers.
Hlaalu's starting office is in Balmora, Redoran's is in.. Oh jeez, been so long, place with the huge Shell. Skor, or Skar, or something? No clue where Telvanni's is.
Pick the one in your favorite town!