CL is the hardest competition in the game, it is 1 win out of 112 players in 8 groups as the previous normal league count as a qualifying round.

Although cup is 1 out of 128, luck is a bigger factor for cup compared to CL as whatever you are facing, if they are in CL they aren't clueless despite the majority of the players are.

The normal league, 1 in 14, is the easiest competition in the game.

As a f2p I've been in CL final three times claiming the title only once at season 6. At higher levels it becomes even harder. Most winners of it are heavy spenders.