I've tried a lot of Nilgiri teas, and what I find in their flavor isn't anything like Assam. Assam is quite malty but Nilgiris are crisp, like a cross between Ceylon and Darjeeling. I usually detect a citrus flavor as well.
The best Nilgiris I've had have been from the Glendale Estate. There is a "Handmade" that TeaSource sells, as well as an OP version (which is harder to find). Tao of Tea sells a similar large-leafed Nilgiri they call Neela. They don't specify what estate it's from, though.
Craigmore, Dunsandle, and Tiger Hill are also good estates. I really disliked Chamraj and Kairbetta, though, they were quite bitter.