[rphlx]

> ... no obvious way to tell which is the One True Chain.

One obvious way - whether you agree with it or not - is to use hashrate. It's quite unlikely that both chains will have a nearly-equal hashrate for a sustained period of time.

[TD-Linux]

That's probably a bad idea - miners target profits. There was a lot of oscillation in hashrate when BCH split - and it had a lot less support. It briefly exceeded Bitcoin's hashrate. http://fork.lol/pow/hashrate