Talon is an assassin, who jumps out of the bush and uses massive burst damage to kill people. He also have a lot of powerful AOE moves, like his Rake. However, he is very hard to play, and also has mana problems early game.
Nidalee has that spear thing that does crazy amounts of damage. It is possibly the greatest poking move in the game. However, Nidalee does turn into more of a support late game. Also, she turns into a cougar, and possibly has the best escaping toolkit in the game.
I've never tried Fizz before, but he has great mobility with his toolkit, and you can dodge almost every move in the game if you time his poll vault right.