trust is probably the biggest factor nowadays. Check this post by
@UnusualSubstance out:
https://www.blackhatworld.com/seo/trust-becomes-the-most-important-ranking-factor.1749503/
After trust I would say it's either authority (ie. backlinks + number of rankings + traffic volumes + time you've been ranking for), or user engagement, it's just that I'm not sure which one is more important (probably that user engagement, but in some niches authority is probably still more important than user engagement, so it depends)
I think for local SEO it makes sense to have a GMB especially for that extra trust factor.
All main socials.
I would focus on YouTube and Reddit for their massive authority power.
For YouTube videos I would just screen record all reviews one by one and schedule them out for years to come.
For example,
Say my business name is Remis Nudes.
YouTube title:
Remi Nudes Review By (first name of reviewer)
"Hey everyone CEO of Remis Nudes here and today I'm gonna briefly shout out to yet another glowing 5 star review from John.
You see we worked with John on... Blah blah
"Thanks for the review, John!"
If you want results like John be sure to check out (URL)."
Bonus points for sharing your video on Reddit for that double damage.
PS: This has the advantage of making your past reviewers feel famous by being shouted out so if they're paying a subscription they'll
probably stay longer.
(Reducing customer churn is huuuuuuuuge, btw)
Absolutely no data to support that but it does make logical sense at least to me.
Edit: The YouTube idea will work for essentially any business by the way not just local. I got a bit carried away lol.