What I need to enjoy the game.

Hello, so I have been playing for a while and never really found a champion I like other than Zed who I rarely play now since he is basically permabanned. I have been asking questions about a main for a while and still haven't really found one I truly enjoy. I have realized what I want however. I know I want a midlaner that can also be played in another role if needed (making their availability higher). I like the casters and assassins, just hard to find which one. I really want someone that is difficult and has a high skill cap so you can always improve on them and learn new things. Also someone that you can just spam and always enjoy (I realize this is kind of opinion based, but most people find fun in the same people). So really someone that is really hard with a high skill cap, you can spam, and can be played in another role if needed (Though this is least important). Also, I get bored trying to really learn a champ except for a few fun ones I have found, which have been easier champs you can learn in 10-20 games. So any tips on spamming a champion and not getting bored of them. Thanks in advanced!

EDIT: I realize it is good to know a variety of champs which I already do, but whenever I see someone who also knows just one champ insanely well I feel like I really need that to enjoy the game. Thanks in advanced!