The game for new players is not about which champions are best; it's usually about how you like to play the game, your skill level, and what mechanics appeal to you most as a player. Some off-meta champs really click for me, but don't click for a friend of mine. Or, similarly, everyone says that Katarina, a melee-range AP assassin is one of the most broken champions in the game and will reliably dominate her lane, but when playing her, I couldn't get the hang of her mechanics.
However, later, I used another melee-range AP assassin, Ekko, and I did pretty well on my first try. Similarly, when I have to jungle, I usually pick Sion, who everyone says is kind of bad right now, even after his massive rework that made him strong again. What champions have you played, and do you like so far? I could definitely recommend some powerful champions based on ones that you like so far.