I have used Vodafone for around two years because of its network coverage, If we talk about vodafone, my phone even was cating internet at Nepal I was shocked to see and when I made call to check whether its really working it cut 95 INR per minutes hehe.
In terms of plans it has the highest prices rate in India, their plans are so expensive that I had to port my sim to another operator, I do not about their postpaid service but their prepaid service is good, customer care executive talk very calmly and friendly and as a professional they have the best service because they are Expensive.
I personally recommend Vodafone.