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), 1 completed item, and lategame with his weak point being between 1~2 items, which if you stop early you get to basically skip to lategame panth(3 items). As someone who has 1.5m points on him I can tell you he’s piss easy to play, stomp and cheese midlaners with early game. He sets up ganks effortlessly and is a good early skirmisher and after you snowball mid you have the perfect ability to jump and completely swing sidelines(usually bot) to get very easy quick games 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.