Well, I would say we need every year new tank and dmg sets, so that people can spend nuggets on current events not just waiting for christmas, also that everybody who is new can keep up with game with good sets.
True is Bull needs to be updated and so is Astor. In general we need more FF sets, dmg, tank and buff sets. I dont see problem having 2-3 tank sets released in 24 months so is dmg set. They dont have to be all the same, you can add different bonuses to each of them so that people can choose or make nice combination from sets. I would stop making sets with sector bonuses dmg and attack, but focus more on defence and resistance... being tank sucks now .... Let people play with their own bonus so that tanks arent vanquished too soon as a bug.... Now we have black heart set that gives +17 attack sector bonus and to dodge this you need every God behind you lol