Airtel is on the verge of decreasing the data limit from 1.5/1.4 gb to 1gb in certain plans. So, it is wise to opt for 1-year plan to lock ourself with 1.4gb per day for longer. However, the additional benefit of recharging on every 82/84/90 days is that we get some extra GB (currently 5), when we recharge before the expiry date. So, eventually, for 3 to 4 recharges per year, we'd accumulated 15/20gb instead of just 5gb from one time recharge of 1699. So, both has its own pros and cons.