Best Current Team Comp?

Hey all! I have started playing ranked this season. I began in Bronze 3, worked myself up to Bronze 1, then just recently got demoted to Bronze 2 again. This is the result of a small losing streak of 2-3 games. I feel that if I can choose a champion that better fits my team then i can prevent losing streaks like this, because I have had games where the enemy team comp was simply far superior to us and won once they grouped. Any advice on good team comps and champions that fit them? I know it is not an easy question to answer but I'm trying to rank up, and beside improving in map awareness and decision making I would also like to go into the game knowing our team can synergize late game.