NPM stats are not representative at all because for every big project there are tons of NPM downloads. For every branch, every deploy, every pull request. This grows exponentially.

Just like Github stars arent representative because only (active) Github users would add a star and when a project has critical mass, the amount of actual users will no longer correlate to the amount of stars.

Anyway, I don't think there is a good way to measure usage or popularity of these frameworks. Maybe Google Trends or stackoverflow tags? I don't know really.