it depends...
If the old article has zero links, zero traffic and zero authority (UR) you're much better off trying your luck with the new article.
If the old article does have all of the above (links, traffic, decent UR) it's obviously better than the new article.
These being said, if the old article already has several or more links that point to other sites (NOT to other pages on the same site, but to other sites) and your link will be buried deep on the page you will get almost no authority (you might still get traffic though if that page does get traffic in some way), so it's pointless to have a link there.
Likewise, if any of the 2 articles (old or new) doesn't give a d0follow link it might not be worth the investment (although, if the link is placed on a big site like Forbes, NY Times, etc) it can still be a good link because of the trust that google has in these sites...
So, like I said, it depends on a lot of things so you gotta weigh all of the pros and cons of both scenarios, such as:
- the authority (DR) of the site that gives you the backlink
- the trust that google has in the website that gives you the backlink (trust is hard to assess, you have to guess it most of the time, but as a general rule, if that site is big and popular, ie. gets millions of visitors a month, it's safe to assume that google trusts the site)
- the authority (UR) of the page that gives you the link
- where on the page your link is placed (the first 2 external links on a page tend to get most of the link juice / authority, so if your link is 5th or 6th on the page it might not be worth getting this link even if the page has good UR)
- whether or not the link is d0follow (you want d0follow links most of the time, if that's not possible and the link is nofollow at least make sure the site is trusted by google, ie. is popular enough to at least send you some traffic or for google not to tank it)
- whether or not the page gets traffic in some way (preferably, you want the page where your link is to get traffic both from other pages on that site, but also in other ways like google, reddit, youtube, magazines, forums, etc... the more sources the better)
- (if traffic doesn't exist on that page) at least make sure that the page is not buried deep into the site where no one can ever find it... and also make sure it's indexed in google or other meaningful search engine...
The last point is not very important, but it can become important in certain scenarios (which I can't think of at the moment, but they do exist!)
I hope I explained well...