Top three for me are Fizz, Twisted Fate, and Amumu.
Fizz is a nice mixture of heavy burst damage with the ability to get out of most situations unhurt thanks to playful/trickster. and His shark once he has his AP built up can rip apart any champ who was foolish enough not to stack Magic resist. Also people find him annoying and I love that about him.
Twisted Fate looks easy but his card timing takes practice to learn but when you do chain stunning becomes easy combined with his Q and a Lichbane that 3 hit combo is deadly and anything that survives to run can be chased down with a quick teleport from his ult.
and finally Amumu recently started playing this little cry baby and I have to say he is evil if you catch someone just hug them and watch them melt…also his jungle is really fun.