I find that jungo and junks work well, jungo boost the high life you get through winning making it hard to catch up and junks have cards like gil,rowdy,tremorh and gibson which you can save your pills for jungo so those clans work best for me, what clans work for you?
I would say clans with good DR, because in later stages with reduced pillz it's obvious that you can't win with every card, so you have to sacrifice some and the point is to make that sacrifice as less painfull damage wise as possible. although on the other hand I recently got 19 wins with my standard Rescue ELO deck which had only Steve as a DR (and I haven't played much survivor before), so it all boils down to strategy, your familiarity with the deck you use and of course luck.
I like using freaks, the poison can be a great dealbreaker especially later on. Lets say you have 15 life and your opponent has 12. If you get the posion in this causes for a great difference in life, all you need is some DR or just a second win and your opponent is mostly done for. (elo mode)