IMO the best place is whatever subreddit best describes that exact topic. I've found technical subreddits to be welcoming of thoughtful, well-written articles (in contrast to much of the rest of reddit which tends to frown upon self-promotion). I've gotten thousands of referrals back to my site on numerous occasions.
Somewhere that's often hyped but is _not_ any good is Dev.to I carried out an experiment with posting a series of articles there and counted how many referrals I got back to my website. Average like 5 per article. Not worth the time to submit. Avoid.
>The quickest way to receive an invitation is to talk to someone you recognize from the site or request one in chat (https://lobste.rs/chat). If you wrote a link that was posted, definitely contact someone for an invite, we'd love to have you in the discussion.
I requested an invite on #lobsters and a member responded via dm to verify my profile (GitHub/twitter/etc) and then sent an email with the invitation. Best time would be during the US work hours, since the channel is more active during that time.