I think that price is the best way. If moon, it means people are excited, if dump, it means people like fiat more than btc.
Personally I think this is a really bad way to measure popularity. Price discovery due to the hodl mentality of most bitcoiners is imo quite bad.
...
price down: bitcoin doomed
price up: bitcoin moon
i would look at transactions or
https://panteracapital.com/bitindex/