I’m going to go and say pantheon for the least effort for the absolute highest reward. Pantheon’s spikes are his early game(Lv1-6), almost first completed item, and lategame with his weak point being between 1~2 items, which if you stomp early but the game still didn’t end you actually get to essentially skip his one big weak phase straight to lategame panth(2.5+ items). As someone who has 1.5m points on him I can tell you he’s piss easy to play, stomp and solo cheese midlaners with early game. He also sets up ganks effortlessly and is a good early skirmisher and as you’re beating mid you have the perfect ability to jump and completely swing sidelines(usually bot) to get very easy quick ffs and game-ends with close to no mastery required.

Best carry potential in mid for all lower elos below diamond after which you gradually start getting punished by some matchups.