I know most people would say Garen is the "easiest" or most "noob" friendly champion, but I have to disagree.
Sion is the most braindead champion in this game that completely breaks the fundamentals of this game aka laning phase or the importance of it.
The new inting sion start just proves it. Everything about this champion - the way he farms, the way he gets tanky, the way he clears waves, his ridiculously low mana costs (anyone ever seen a sion run out of mana? me either), his ability to farm even after he feeds his ass off ...
This champion is the true, ultimate noob champion that will be useful with all his CC even after 20 deaths and 0 farm.
In my humble opinion, after his rework the game went down the hole and the entire game was dumbed down for 12 year old kids.
I'm talking all the little things after that which contributed to this game being easy and less punishing for garbage players.
I guess that's when Riot changed their philosophy 180 degrees because they were acquired by Tencent.
Every other champion / rework after that just was completely braindead and impossible to shut down.
I just had to play against a silver Sion who I couldn't kill no matter what, I couldn't stop him from farming at all while the rest of my team was feeding.
Edit : Did I mention that his Q goes on a lower cooldown if you actually outplay the braindead Sion and cancel it using your stun? So if he misplays and makes it last long enough for you to stun him and break the channel he is rewarded with reduced cooldown timer on his ulti.
Also, his cooldowns are so ridiculously low he doesn't have to worry about trades whatsoever.
This champion is the epitome of bad design, in my opinion, and I know many people will disagree, but every Sion main should be at least 5-6 divisions lower than he is right now, same goes for some other champions that are so ridiculously easy and hard to shut down they artificially elevate the player's skill well above the division he deserves