Provided you have Guru Cr or DJ Korr Cr, Junkz and Sakrohm are probably the best. Otherwise, Uppers, Ulu Watu, Montana, Nightmare are all pretty strong.
For extended, any combo of Uppers, Sakrohm and Skeelz.
Uppers is quite powerful w/ Jackie Cr, Dorian, Lady, Herman, Hefty, Glenn, etc.
Sakrohm is also strong w/ Stella, Graks, Uranus
Skeelz got a solid lineup w/ Caelus Cr, Michael, Dwan, Minerva, Tomas, etc.'
Ulu Watu is great T2 w/ Tan Man, Serena, Stanly, Wee Lee, Lulabee, Miss Lulabee, Oraya, Hikiyousan
Sakrohm/Uppers with Morphun to me is the most optimal t2 survivor deck out there as of right now. I find myself starting every preset with Morphun, GraksmxxT, Uranus, Virginia, Jackie Cr, Lady, and Maurice. The last slot is really just a personal preference since I don't own Guru Cr as of now, but if I did, I would consider that last staple in the deck. So, basically I personally think there is no better deck to play in survivor than the one I just listed, simply because of its versatility. Other strong clans for Survivor are the Skeelz, Sentinals (for those who are on a budget) and possibly Junkz if you own DJ Korr Cr, if not, I really wouldn't bother with them. Hope this helps.