In terms of reaching lots of people I haven't had much luck with either Threads or Bluesky to be honest. I tried both, and I wasn't really that impressed with crickets. The best are chronological feeds with or without keywords/hashtag searching. For that, I stay loyal to open source, federated systems. I get more eyes on chronologically-based social media than either of any of these corporate ones.
Mastodon: open-source, in the fediverse, open for signups (depending on the instance)
Bluesky: proprietary, invite-only (for now), not in the fediverse but has its own network of domains
I don't get the appeal of Threads, even if it wasn't run by Zuck. There's no Followed tab, you see literally everyone unless you decide to mute everything you do t want (which is a lot), and the search sucks. Oh, and it's not in chronological order.