I recently switched over to BSNL. My initial plan was to go for an unlimited plan. However later I plumped for the 600 rupees plan. And I am happy. To begin with they are giving me 20% rebate on the bill. I think they have some scheme going at the moment. The unlimited is currently available for 500 or 550.
Now for 480 rupees per month I get 2.5 gb of data per month and nights (2 to 8am) are free download. The speed is amazing. The connection is also extremely stable and reliable. Initially I was skeptical about whether the 2.5 gb will be sufficient for me. I as well as my wife often use VPN for office work. However as I found out it more than suffices for us. Only that I schedule all downloads after 2 pm. I find that I can schedule multiple downloads every night and yet they all finish within the free time. This when each of them may very well be of 1 gb or more at times. Speed at over 250 kbps (actual) is just too good by Indian standards.
I think one can look at BSNL plans. Oh! By the way, the telephone comes free in that 480 bucks and I even get 50 calls free. Beat that.
P.S. Stated speed for my plan is 2mbps. But I find I get upto 550 kbps depending on the server at the other end.