There was a scientific paper I read semi recently that showed that researchers who post on Mastodon get much higher quality interaction than on Twitter (and I think a few other social-media type places, but it was mainly Mastodon vs Twitter). There was overall less interaction on Mastodon (unsurprisingly), but also that this difference has been diminishing as Mastodon grows. My takeaway is that if you want engagement, go Mastodon.