Preprints.org is a new site for sharing preprints of papers.
arXiv is one of the longest standing, stable and mature places for many people.
I'm wondering where to upload a paper (which is already open access on GitHub, but not very visible).
One downside of arXiv: Google Scholar seems to direct people to the arXiv and not the latest versions.
One upside of arXiv is that it is open, stable and mature.
In summary, where should I put my preprint for maximum benefit?
Update
Thanks to the first link in the 'correct' answer below, I think I've discovered the OSF affiliated preprint services. See here for more info: Preprint services other than arXiv (for other fields)
Check it out (and potentially submit your preprints) here: https://osf.io/preprints/