My first 3150IP champion was Akali. She was very fun and I picked her up at level 10, I used her from 10-30 then got really bored with her. She has high mobility, high burst, and stealth. She stomps people at low skill cap, but, as you move to smarter/better players, she gets countered hard. But, still, even if they're good, but you're better, you will still do well with her. The problems with Akali are: Her jukes and escape mechanism are highly surrounding reliant (enemy champion, enemy minions), she gets boring as you continue to play her, and her stealth is crippled by oracles. But as mentioned before, try free champions. Don't blindly buy a champion. I brought Akali after I lost to one hard.