Survival is better, there's not a whole lot of debate. More constant damage and more CC. Rets play with classes that do sustained damage because Ret already brings burst and if you put two burst classes together it basically means the other team just pops all their defensives when you pop burst and then they're not in danger anymore.
Regardless though, if your goal is 2k you guys can get that with him being any of the 3 specs, doesn't make a massive difference.