well, i would say go for Airtel 1099 plan which gives 384kbps in day and 1 Mbps at night. that's a really good plan if you compare it with MTNL 1299 plan.
384kbps plan in airtel gives 45 to 50KBps download speed and 512 Kbps plan on MTNL gives 55KBps. so the difference is marginal and you get 1Mbps at night.
But keep in mind the fair usage policy of airtel. it's 100 GB i think.
Whats the plan name, Kinldy provide me the link.
I saw a plan there, here are the details.
swift 1099
Browse and download faster @ 512kbps
Speed @ Day 512Kbps
Speed @ Night 512Kbps
Data Transfer Limit Unlimited