VSNL - I have been using their service since I can remember doing something on the https:// They are surely the best among the other Dial Ups. I have used almost all the Dial Up provider services. To name a few - Satyam, NOW, TataNova, Netkracker, Eth, BPL, gosh ... so many I may have forgotten a few of them. I would rate VSNL as 1, Tatanova as @, and ETH as 3, and others not rated the better. But, overall the dial up scene in India is very bad. Whenever I go to Dubai and use the service is like a ISDN line giving a speed of 64K, which none of the Dial ups give here. Another major problem, besides speed and hanging of the line, is the frequent disconnection, it is so frustrating, once the site loads, it disconnects, and user is left with no choice but to reconnect.
The customer service of all the dial ups is very good, although the VSNL customer service people may not have the sweet voice, but, they know their job and they do it well, to solve problems, which rarely come by.
Now, I am using the DSL, it is fantastic, the customer service is very very very poor, but, when it is working it is very good. The line goes down every week for atleast 3-4 hours, but it is still good. It is expensive, but worth it, for business people who are on net most of the time.