Subscriber count is useless, because users are subscribed to all subs by default unless the sub opts out, hence many very dead subs clearly visited by only two users in their entire existence having 30,000 subscribers.

(I happen to think the opt out subscription choice for this site is super dumb but whatever)

I'd suggest finding subs on a topic you're interested in, and then trying to get other people interested in also participating in them. There's a group of new users interested in getting non political subs up and active, you can see me interacting with a few of them in my comment history. I've basically been going through comments of people I talk with to find other people they've talked with to find any subs they've posted to. Slightly stalkerish but oh well.

(maybe I should make a post on s/whatever to coordinate this sort of thing more formally)