Champions that remain fun even if you spam them:
Very mobile, flexible, good split and teamfights, easy to pick up, but does take time and commitment to learn CORRECTLY. Biggest con would be the current itemization for her is very weird/punishing for inexperienced players and has a hard time with ranged matchups.
Very fun and fast paced, splitpusher, easy to pick up, very good at punishing bad players, good at dealing with tanks. Has kind of a hard time against other bruisers in the early game but has a lot of room to outplay.
Sets up ganks really easily, mobile, tanky with good teamfighting, mainly focused on punishing other teams carries or misplaced targets, has a ton of hard matchups top so might not be the best choise.
The King of top lane, playing Renek will teach you trading patterns, understanding power spikes, wave management, tower dives. Very good sustain, one of the strongest early games and a decent late game. Can carry games easily in low elo because players dont respect your all in potencial.
Hypermobile with tons of teamfight potencial, can solo carry games on her own if gets fed, and can always comeback into the game once she gets 2-3 items. Good sustain, tanky, her passive and Q resets make her very fun to play as.
Huge level 1 that most low elo people dont respect, has really good poke vs melee and her mobility and shroud make her very hard to gank, good learning curve.
Off meta pick, very versatile builds means you can adjust to your teams needs, really good poke, roams really easily, most players dont know how to play against since its not very common to see, definately a good learning curve but really easy to pick up. Her heals, mobility make her pretty safe allowing you some room when you misposition.
Another off meta pick, once again most players dont know what to do versus you, you can build squishy oneshotter or tanky oneshotter whatever you prefer, very good at roaming thus you can take your lead to other lanes.
i could go on with more champions but these are my personal favorites/pocketpicks.