I like Grayson better as Nightwing. He was the best Robin no doubt, but I also liked Jason Todd, although I prefer him as Red Hood. Damian Wayne is better than Tim Drake though, only slightly but still.
I actually agree with your order and what you said. Though Grayson was awesome as Robin... He's still a top 20 superhero off all time in his own right as Nightwing and you have to believe that's a bit more impressive than being a great side-kick. Being a great side-kick isn't as memorable as being a great super hero.