Which champion do you guys think is the best, worst, easiest to play, and hardest to master?

I've been wondering lately, which champion in League of Legends is the worst, and no, I'm not a foxdrop fanboi, my brother made this account and made me start at level 11. It came to my mind that Urgot was the worst cause of his lame ult, but his passive isn't too bad. After thinking about this, I wondered who was the best, which lead to which champion is the hardest to master, and easiest to play. I thought that in my opinion, their is no best champion, because the meta always changes, and most champs are strong and weak, determined by skill, and map awareness. The easiest champion to play I thought was either Katarina(Cause you just mashed your keyboard) , Ryze (Since he has no skillshots), Riven (Cause you mashed your keyboard like Katarina) and Teemo. It came to a conclusion that Teemo was the easiest because you would just poke them with darts and if they relied on basic attacks, when they come close just blind them, and shoot them. Plant shrooms everywhere around top lane and when the enemy jungler tries to gank you'll already know, or you just kill him/her. I thought Ryze wasn't hard to play, but after watching my level 30 friend (who has recently become level 30) played Ryze , he had to look at his keyboard for like 2 seconds find and click q and then click on the enemy, but if it was someone who moves around a lot (Yasuo , he couldn't click on him. I remember seeing him Zilean and he couldn't ult my other friend because he was playing Yasuo and just ulted himself instead. I don't understand why, but I guess he'll have to learn in time, especially since he doesn't use quickcast, he can't spam his abilities too well. I thought Riven and Katarina were easy, but I saw that my friend couldn't mash his keyboard, kind of same thing with my explanation of why Ryze is hard for some people. I obviously knew who was the hardest champion to master and play. It was Zed . You'd have to be a ninja and assassinate someone. I might be wrong, but let me know in the comments on what you think! Thanks for the feedback!