In term of store of value, no other coin or real-world asset can compete with bitcoin at this point of time. However, it certainly doesn't mean that it will not be possible in future as well. As of now ETH looks like the closest contender of bitcoin in terms of market cap. Even though the difference is huge, but the second highest market cap belongs to ETH only. Also ETH is technologically superior that bitcoin. While bitcoin transaction takes about 30 minutes to confirm, ETH offers near instant transactions. That is the reason why ETH has become the number one choice for the arbitragers. So my answer is ETH which can compete with bitcoin in future.