Well, Airtel 3g has better speeds than Reliance Netconnect and Tata Photon Plus. Tata photon plus gives around 512kbps to 1 Mbps average, I have tata photon plus, so I know.
Airtel gives avg 1.5-3.5 Mbps, with bursts of 4-5+ Mbps.
Reliance 3g may be better than Airtel 3g in terms of speed, but definitely not Reliance Netconnect.
For browsing, 3 Mbps or 6 Mbps doesn't really make much of a difference if you can get away with 1/3rd the committed amount with the flexibility of increasing the data usage as per your requirement.
However, if you are ready for 10+ GB each month, you can go with Reliance.
Although, my personal experience with Airtel's CC has been much better than with Reliance.