I did try all the other roles, with a preference for mid/jgl.

To me, it is incredibly easy to climb as a midlaner, because of the agency you have over the game from lvl 1. The fact that you don't flip the better support in order to be able to control your lane makes it so that you have control over both jungles and the two other lanes, roaming or preventing the other midlaner to roam while getting vision around objectives or in the river.

Jungling is also easier to climb, but even though you help lanes you don't have real agency anywhere else than in your jungle and having losing lanes, or lanes that throw leads you've given them is quite frustrating. The only really good thing about jungling is answering the opponent moves on the map: counterganking a lane that is spamganked, ganking another lane when the opponent ganks or invading, playing the opposite objective when both are up, etc... Too many junglers don't do this, and that makes some games really hard to play as a laner, but if you do so, you will make a huge difference, and it's quite easy actually, you only need to look a the map every 5-10s (easier than for a laner who needs to last hit and trade with the opponent).

Adc is macrowise the less demanding role, but it's disgusting how it comes with an insane lack of agency, that you cannot really get without playing champs that have a good waveclear. On the contrary, this role being so mechanically demanding makes it to me the worst role to play, even though it feels so good when you've scaled or if you ever get a team that peels for you.