Both are different. It depends upon your priority.
If you want fast trade like we had during the times of Coinsecure or Zebpay then go for WazirX. But there is one catch while using WazirX. P2P network of WazirX is mostly anonymous. You won't know the details of buyers like you do in case of other P2P. Like normal exchange anyone can buy your USDT by sending money in your account. It may not be fully safe. They have option of 'Preferred Buyer or Seller' but it ain't the same thing.
Whereas in case of LocalBitcoins, you can see the details of buyers before selling which provides more security.