Underrated Spider-Man villains

1. doctor octopus
2. Sandman
3. LIZARD

One of the most under rated?

I'd say
1. Rhino
2. Kingpin
3. Green Goblin's son (Harry)
That's all I can think of.

Jackel
He's a top tier spider-man villain, and no one talks about him.

So far, Black Cat (Full Potential) is Spider Man's most underrated enemy and many have even blasphemed her!

Black Cat is one of the under rated though she's a neutral character.

I'd say Scorpion. He was Venom for a time and gave Venom the reputation he still has today. Scorpions and Spiders are related and natural enemies in real life so he could have been Spider-man's best villains. Unfortunately writers made him just some deranged hit man who Spider-Man can take out with ease.