Idk about users but measurable engagement is higher on NOSTR than either. A post with 100 likes is rare even on big Fedi servers, whereas it's not uncommon to approach several hundred on NOSTR, maybe even near 1,000 on rare occasions.

For comparison, Gab at its peak after January 6 had lots of posts with 1,000 or more likes, and the most popular ones were between 10,000 and 20,000 (It's not even 10% of that anymore, but it gives a decent measure for how active edgy alt tech can be vs how active we actually are atm.)