Champions that are worth maining but have low floor and high ceiling.

What are some champions, that i can pick up but that are still somewhat flashy so i can learn something new all the time. I dont want to play full tank champs so preferably i would like to play one that has some diversity. I dont really know what playstyle fits me yet tho. I found playing asassins and mages fun but i just sucked at them. I switched to some tankier champs and played way better. I know that losing when playing higher skill champs is normal but are there any champs that a beginner can play but have a lot of room for improvement?