Ekko or Riven?
I want a melee champ to main, but I can't decide which to choose. Help?
I want a melee champ to main, but I can't decide which to choose. Help?
Neither
Neither, try someone who isn't a toxic champion, have a go at

Sorry, but Rengar is toxic and Cho is MEGA toxic.
How the heck is an immobile bruiser toxic? Also how the heck is a squishy with no escape toxi?
Cho: Insane sustain from his passive. The only time he ever has to leave lane is to buy stuff. An AoE knockup that does RIDICULOUS damage. An AoE silence that lasts forever and does great damage. Free ranged harass just from auto attacking. An ult that does stupid amounts of true damage AND makes him (a mage) as tanky as a Sion. Only weakness: low mobility even though he has one of the highest base movement speeds in the game. He is almost the poster boy for toxic.
Rengar: No idea why you think he's squishy. He gets bonus armor and MR from one of his abilities. No escape? He has one of the best slows in the game AND a stealth ultimate.
Try someone that won't make you look like you want to stay in bronze 7, like Wukong.
Go for
or if you want to be super Hipster go 
Ekko is easier to do well with if you're behind.

Ekko isnt really melee. Hes a spell caster that benefits from on hit effects (like lichbane)