For me bitcoin is the digital gold, it is shown already after several crisises that people go in bitcoin as a safe heaven / store of value. Nothing beats Bitcoin in its use as store of value. Ethereum is a platform for smart contracts, maybe an good investment, but not designed to be a deflational currency like bitcoin. Lightcoin is so small that you cannot take it serious yet in the mainstream investor world (where most of the money is), its not even comparable as silver when you compare bitcoin to gold. Beside that the blockchain is way less secure and security is what investors are looking for in a SAFE heaven. The high use of electricity is a good thing, it's the root of the proof of work concept what makes Bitcoin so incredible secure.
I agree that the proof of work concept is good for Bitcoin (even if it does require a lot of energy), but my main point was that gold cannot be copied or changed.