Nobody mentioned Black Adam 🤔

He's an anti-hero now.

Anti-villain.

Still not a proper villain.

Sympathetic villains are still villains. Black Adam had so many redemption arcs, but he's not on the hero side of the spectrum.

He's in the justice league and from how he's been acting up till now I'd say he's more closer to a hero than a villain.

He's been there before. He can't hold on to it.

Not like this he hasn't. The closest he came was when he was with Isis or when he had joined the JSA but in both of those arcs he openly expressed his opinion about ripping the criminals apart and sometimes he actually even did do that but so far in the justice league run he hasn't even tried or said anything about killing the villains. I do agree with you though, he can't hold on to it but his current status still remains tilted more towards hero than villain.

Deathstroke is pretty fan favourite. He's had 4 comic runs in the past 10 years along with generous appearances in other media

The riddler