No other European *A airline offers the sort of coverage in India that LH does. TG or SQ are similar in terms of coverage in India but involve significant detours and would be more expensive when heading to Europe.

Outside of Star Alliance, BA offers flights from many airports in India, but their economy mileage earning is even poorer than LH's. There are also the various carriers based around the Gulf, but I don't think any of them fly to Prague yet.

The answer you seek may not be switching airlines, but switching programmes. You might consider collecting miles with United Airlines instead - they offer 100% miles even on the cheapest longhaul fare classes on Lufthansa. If you fly enough miles to make FTL with LH, you could even make it to UA*G with little or no additional effort.