MRCC is hands-down the best card out there for 6k transactions every month. Even works great for 20k worth transactions every month!
The availability issue is more so for the exploiters and resellers. For an average user, it will still suffice for your transactions.
You can also buy Swiggy/Uber/Myntra vouchers, they work great too!
Or just swipe the card normally for 1500x4 transactions every month and you will still get 1000 bonus MR points.