Community/togetherness -- Since leaving Reddit, I feel more 'lonely'? Being here definitely scratches the social-itch.
Positivity -- Wholesome people and productive conversations.
Humour -- Some of the comments/posts on Reddit were wonderfully dry and/or edgy. One that made me giggle recently: "Avoid being misgendered at checkout by not paying :)"
News -- Following centrist/neutral subreddits, and r/outoftheloop was great too.
Niche interests -- As said in OP!
I think the only issue we may have is niche interests -- the other points are not contingent on 'size'. Loving what's here so far <3