That it can't be hacked/money stolen/that it works/that its economic model is solid. There are a lot of assumptions that btc gave us that these newer projects haven't proven themselves
PoW has a tendency for centralization via 51% attack, which is why eventually we might not be using BCH, as it shares this flaw with BTC, for memo.cash.
That centralization is fine because 51% is not really a big deal. Still censorship free, all old txs untouchable. That alone is worlds better than legacy.