I guess you have the answer already that there's no other good store of value none other than bitcoin.

I've known someone personally who's holding Monero more than bitcoin and they are mining it. The price target for him to sell his XMRs is $1k+ which is really high. But he treats it as a store of value more than bitcoin, so it depends on how good the coin is and the treatment a holder gives to that specific coin which can be a store of value but for me still bitcoin's the best.