If you're talking for SEO then it depends on keyword competition and quality of content.
For highly competitive keywords, you'll need to produce in-depth articles with a least 1000 words. I'm not saying 1000 words because it is a standard or something. It's just that there is this misconception that you need at least 1000 words to rank well in Google. So most of the articles you find on page one, for a competitive keyword, will have at least 1000 words in them.
I've ranked pages with even 500 words in top 3 but they are low competition keywords and the other results on page 1 didn't have useful or relevant content.
Basically, I would suggest do keyword research and search those keywords in Google. Look at the top 4-5 search results. If they're really long-form content, then sadly you'll have to write long content too. If they're short content, then you can rank well with shorter content.
As far as sharing is concerned, if your content is useful, it will be shared. If it is also unique or new, it will be shared even faster. It doesn't depend on the length.