Gonna be 4th form Frieza to for me. The sleak design makes him look dangerous because it looks so different than the other.
Honorable mention to first form Frieza. At that point on the arc, Frieza's power was completely shrouded in mystery. No one ever really knew just how strong he was, only that he was the most powerful. He never even got out of his chair lol
Then you got a glimpse of what he's capable of when he fights Nail. It was a real "WTF" moment for me as a kid.
Real impish design
And Golden Frieza is the best idea to come out of Super. 10 years ago there was no way you could convince me that I'd be happy Frieza came back. On paper, it annoys me. But the way he returned with the Golden form and ends up being an MVP with Goku and 17?? I can't wait to see when the story goes back to what the hell he's up to.