I'm not sure how it affects ranking, but it does make your website more secure and safe if someone visits it. I personally feel a lot safer if I visit a site that has SSL, especially if you are selling something like a service etc.
Wordpress's move to limit features leads to a logical demotion from G on non-https links.
Not all sites are transactional so logically do not require the cert so G can not blanket demote link value.
With this information, we can assume Google will only ever (let's just say the next 5 years) give a marginal boost to https sites, and the OBL from those sites. It makes large-scale networks more complicated and expensive to build and renew but this has been the game since 2008 and in my opinion, the reason why there are so few majoy players at the high end of network ownership (pharma/porn/casino)
If it is a single site, your money site, fuck it why not go for it, its a few $
If its buying links, whatever, diversity is always good
It is now has become a mandate for all the websites to have SSL certiﬁcate installation and it is also well known that SSL certiﬁcate is a ranking factor in Google search results page that helps in improving visibility of the website in google. SSL certiﬁcate encrypts the data transmitted between the web server and the user. Hence, it provides maximum privacy,security, and data handling.