Champion Class Reworks: Assassins or Tanks

As I enjoy playing the game and have faced assassins and tanks on teams from several different roles, I have strong feelings towards these classes. My concern with an assassin rework is that with new assassin play styles tanks will either fall back into the meta or no longer be relevant to the play of the game with split pushing becoming more effective. Now I would like to see tanks and assassins updated they both need it but to those who play the game if assassins get an update tanks become a more effective thing for low elo play and causal play but if tanks get the update first then the drawbacks are consequences are reduced, tanks becoming a new thing after their rework and everyone starts to play tanks and soon we will see team fight comps rise up, and then if assassins were rework then everyone would forget about the tanks for a little bit then assassins would dominate for some time until tanks rejoined, now for causal and low elo play all of this may not be very relevant but I would like to see tanks take a priority over the assassins reworks or better yet just give assassins an item overhaul, and rework tanks along with that. (Grammer and punctuation is probably flawed). I would like to see the community help decided on the rework priority though.